, the First Lecturer of Enzymology at the University of Ljubljana

Richard Klemen was the first teacher of enzymology at the University of Ljubljana. His early career in Ljubljana ended in January 1942 when he moved to Vienna, Austria. During the war he conducted experiments that led him to describe the so-called Hofmann-Klemen effect in clay. Later he was a research assistant and titular associate professor in the field of biochemical technology at the Vienna Technical University and finally a lecturer at the University of Natural Resources in Vienna. His life is an interesting example of a scientist and educator whose Gottscheer German origin would probably prevent him from continuing his career in post-war Yugoslavia. At the same time, he did not achieve in Austria the positions and status that his former colleagues and students had achieved in Slovenia. Although he was almost forgotten, he remains important as the first trained enzymologist and teacher of enzymology in Slovenia. This article also presents his full bibliography.


Introduction
Since its foundation in 1919, the University of Ljubljana (UL), Slovenia, has offered the study of chemistry. The first appointed professor of chemistry was Maks Samec (1881Samec ( -1964, who graduated from the University of Vienna, Austria, in 1904. He was a versatile researcher with broad interests, who after joining UL concentrated on the study of biological polymers, mainly starch. The major part of this research today would fit into the field of physical chemistry, but also analytical, organic chemistry and biochemistry. A hallmark of the first decades of chemical education at the University of Ljubljana was the duality of an academically-oriented and a technically-oriented chemistry programme, which were essentially divided between the Faculty of Arts (Slov.: Filozofska fakulteta) and the Faculty of Technical Sciences (Slov.: Tehniška fakulteta). This duality probably reflects the arrangement of chemistry studies in Vienna at the time, as chemistry courses were offered by both the University of Vienna and Vienna College of Technology (Ger.: Technische Hochschulle; later Vienna University of Technology, TU Wien).
With the expansion of the understanding of enzyme function and structure in the late 1920s, it became clear that a course on enzyme chemistry should be included in the chemistry curriculum of the University of Ljubljana. At about the same time, as Slovenia was still largely dependent on its own agriculture, the need arose to impart specific knowledge about agricultural chemistry.
It is remarkable that the development of biochemistry as an independent scientific discipline is even reflected in educational guidelines at the state level. Biochemical content in higher education has been officially requested by the General University Decree 1 (Slov.: Obča univerzitetna uredba) of 1932, which prescribed the organisation of state universities in the Kingdom of Yugoslavia. In this decree, 35 chairs were defined for the faculties of the arts, including a chair in chemistry (Article 96). It should cover topics of inorganic, organic and physical chemistry as well as biochemistry. For the faculties of agriculture and forestry (Article 102), agricultural chemistry was prescribed, among other fields. At that time the University of Ljubljana did not yet have a faculty specifically devoted to agriculture, which probably played an important role in the decision to include agrochemistry in the chemistry programme of the Faculty of Technical Sciences.
A pioneering role in biochemistry education in Slovenia belongs to Richard Klemen, one of the early students of Maks Samec. Klemen was the first lecturer in enzymol-ogy and agricultural chemistry in Slovenia. The circumstances led him to move from Ljubljana to Vienna, where he was actively involved in biochemical and food technology research and teaching. Nevertheless, his work and career are almost forgotten, both in Slovenia and in Austria, where he spent most of his life.

Training and First Employment of Richard Klemen
Richard Klemen belonged to the German minority in Slovenia, the so-called Gottcheers (Slov.: Kočevarji). Since the 14 th century they were settled in about 170 villages in the wooded south of Slovenia, with the town of Gottchee (Slov.: Kočevje) as their cultural and administrative centre. Richard's parents lived in Tschermoschnitz (Slov.: Črmošnjice), where Richard was born on 24 January 1902 and where he attended primary school. At the age of 10 he enrolled at a grammar school in Ljubljana 2 (Ger.: Kaiserlich-königliche Staats-Oberrealschule, Slov.: Cesarsko-kraljeva državna višja realka; Engl.: Imperial and royal secondary school) with German as the school language. He was an excellent student who in July 1920 graduated from the Realschule with distinction 3 . This falls into the post-war period, when the Austro-Hungarian Empire was dissolved and a new state -the Kingdom of Serbs, Croats and Slovenes -was founded. Accordingly, the language of school education changed from German to Slovenian.
At the age of 18, Richard Klemen was enrolled with the second generation of chemistry students (1920) at the newly founded University of Ljubljana (UL). He graduated on 18 July 1925 with an engineering degree (B. Eng.) in chemistry and was thus the 8 th student to complete chemistry studies at the University of Ljubljana. The diploma thesis, which he completed under the mentorship of Maks Samec, dealt with the staining of starch with iodine 4 . The results of this work were published by Maks Samec in Kolloidchemische Beihefte shortly afterwards 5 .
In 1925/26 Richard Klemen attended a military school for reserve officers in Maribor where he spent 8 months. After completion, he was ranked as second lieutenant in reserve pioneer troops. Immediately thereafter, he returned to Ljubljana to join the group of Maks Samec at the University of Ljubljana as a research assistant, but only for a relatively short period (1 July 1926 to 31 May 1927). This is certainly a consequence of the university's financial problems and years of discussions with the Belgrade administration about the need to maintain a technology-oriented faculty in Ljubljana 6 . Namely, for the last two months at the university, he had to agree to work as laboratory operator for a considerably lower salary.
Richard Klemen appeared on the list of members of the newly-established Yugoslav Chemical Society 7 , with his home address Črmošnjice near Semič, Dolenjska region, not the university address as would be expected for a faculty member. In the years 1927-29 Klemen worked as an expert in a sugar factory in North Croatia. In the first edition of the Index Biologorum almanac 8 , Richard Klemen was listed as an assistant to Professor Samec at the UL Institute of Chemistry, working in the field of physical chemistry, but this probably reflected his status in mid-1927.

Klemen's Connection to Agrochemistry
A part of the Klemen family lived in Gonobitz (after 1918: Konjice, today Slovenske Konjice) in northern Slovenia, where Richard's uncle Ferdinand was town councillor, deputy mayor and mayor in several mandates. He was one of the pro-German local politicians 9 . Richard was very close to his uncle Ferdinand and they visited regularly. In addition, Richard's parents bought a considerable plot of land with vines in a place named Škalce not far from the town of Gonobitz as early as 1900. Apparently the funds for the purchase of vineyards came from wood sold from forests in South Slovenia that were premarital assets of Richard's mother Maria. They still owned a farm in Tschermoschnitz and a vineyard in the Bela Krajina region, and Richard's father Franz was a merchant who, anecdotally, represented the Bavarian coffee substitute factory Kathreiner in the Duchy of Carniola, so that the family could be regarded as well-off (Ulrich Klemen, personal communication).
The connection to family and land in Gonobitz could be the reason Richard was attracted to agriculture. His stage in the state sugar factory in Beli Manastir (September 1927 to January 1929) was the first obvious step in this direction, followed by employment (in 1929) at the agricultural experimental and control station in Maribor (Slov.: Laboratorij državne poskusne in kontrolne postaje v Mariboru) where he held an assistant position. It was during his Maribor stage that he was also adjunct professor (Slov.: pomožni učitelj) of chemistry with agricultural chemistry 10 at the winemaking and fruit-growing secondary school (Slov.: Vinarska in sadjarska šola v Mariboru).
In addition to the routine work in the agricultural station, Klemen was also interested in the basic and applied chemistry. In 1930 his first professional article appeared in the Austrian journal Das Weinland. The subject of the article 11 was a comparative chemical analysis of the leaves of selected grape varieties. His work mainly referred to some earlier publications by German and French authors who suggested that the nutritional status of vines could be determined quantitatively by chemical analysis of individual leaves. Klemen has improved this approach by combining three leaves per vine and determining the average values for the chemical composition. Soil samples were analysed for comparison. Klemen discovered no obvious difference between well-and poorly-fed vines from the Maribor and Konjice vineyards, respectively. The elemental analysis of the vine leaves did not seem to be prognostic for the condition of the vines, and the analysis of the soil could indicate the condition of the vines much better.

Doctorate and Habilitation
After years of financial crisis and the uncertainty to keep the Faculty of Technical Sciences as a constitutive part of the University of Ljubljana, a new law on universities was passed in 1930, according to which all faculties at the then renamed University King Alexander I in Ljubljana were retained 6 . This could be one of the reasons for Klemen's return to the faculty (Figure 1), where he worked as a teaching assistant between 1930 and 1933. His first research topic in Ljubljana had nothing to do with his other scientific activities. He worked with his colleague Janko Kavčič (a future professor of inorganic chemical technology) on a study of coal from various Slovenian mines. The aim of this study was to determine which coal was best suited for heating in the so-called Celus heaters and what is the best practice for heating different types of coal 12  In Ljubljana, Maks Samec' interest in enzymes may have increased as a result of working with Waldschmidt-Leitz, with whom he published the first paper on the enzymatic degradation of starch in 1931. In addition, colloid chemistry, which was at the forefront of chemical research in Ljubljana, was considered to be closely related to enzyme chemistry 16 . The fact that the 1929 Nobel Prize for chemistry was awarded to Arthur Harden and Hans von Euler-Chelpin for their investigations of fermentative enzymes could be important as well. On the part of UL, starch degradation by enzymes was first investigated by Zvonimir Čanić as part of his B. Eng. degree 17 , for which the experiments were carried out in the Waldschmidt-Leitz laboratory in Prague. Next, Richard Klemen joined the Czech group to complete his postdoctoral training in enzymatic techniques. It is easy to see that one year in Prague paved Klemen's way to enzymes, which he studied over the next almost 10 years.
On 20 November 1931 Richard Klemen was appointed a Privatdozent for colloid chemistry and enzyme chemistry at the Faculty of Technical Sciences in Ljubljana (Fig. 2), and on 29 March 1933, by a royal decree, a University Assistant Professor of chemical technology. He appeared in 1934 in the compendium on Education in the Drava Banate (Slov.: Dravska banovina; the administrative province of the Kingdom of Yugoslavia, to which Slovenia largely belonged between 1929 and 1941) as university assistant professor at the Faculty of Technical Sciences responsible for 'agricultural chemistry and work instructions in the analytical and physical laboratory' 18 . It was not until 27 February 1936 that he was appointed honorary lecturer at the Faculty of Arts, although he held lectures and practical courses for students of this faculty since 1934. At first, Richard Klemen continued to supervise students who were completing their degrees under the mentorship of professor Maks Samec, but soon he took on some practical and his own theoretical courses. In Table 1, Klemen's tasks per semester are summarized for the period 1933 to 1942.
Interestingly, Richard Klemen was leading several practical courses in the analytical laboratory, which was located in the premises of the 1 st State Real Gymnasium (essentially the same school he attended from the age of ten to eighteen), which housed several chemical laboratories that belonged to the Faculty of Technical Sciences in the basement. Faculty actually arranged laboratories in this building in the year Richard completed his secondary education, so that this might have played a role in the choice of chemistry studies.
As shown in Table 1, enzymology has been part of chemical education at the University of Ljubljana since 1933. In the first three years of Klemen's teaching there seems to have been little interest in the Chemistry of Ferments course, as neither the time nor the place were fixed in the course description. The same applied to his newly established course on Agricultural Chemistry.
Klemen's teaching and research initially remained largely associated with starch, but soon turned to enzyme biochemistry, as his published works show. He was a co-mentor (mentor M. Samec) for the B.Eng. dissertation by Anton Tepež on pancreatic amylolysis 20 , the results of which were published in the journal of the Yugoslav Chemical Society under the authorship of M. Samec and R. Klemen (1934) under the title A trisaccharide observed in pancreatic amylolysis of erythroamyloses 21 . Although today obsolete, the starch subspecies were divided in the 1930s into amyloamylose and erythroamylose, based on iodine staining 22 .
In the mid-1930s there was a gap in the published articles, but from 1938 the publications began to take on a new dynamic. Klemen's next article came from the field of analytical biochemistry and appeared in 1938 in the journal Biochemische Zeitschrift. It dealt with influence of nitrogenous compounds on the determination of maltose by two established methods 23 . This work was also presented at the natural science conference in Ljubljana in February 1938 and published in conference proceedings 24 a year later in Slovenian language.
In continuing his early work on amylolysis with the help of his student Dušan Stucin, whom he supervised for his B.Eng. dissertation entitled Contribution to kinetics of amylolysis in wheat autolysates 25 , an accompanying work on yeast autolysates was published 26 in Biochemische Zeitschrift in 1939. Another enzymes-related contribution from the late 1930s was Klemen's supervision of a B.Eng. thesis of Karel Andreč on amylase 27 .
In memory of the work of the late Johan Rudolf Katz (1880Katz ( -1938, an important Dutch colloid chemist, a special edition of Kolloid-Beihefte was published in March 1939. In this issue an article appeared 28 which contained results of Richard Klemen and Zvonimir Čanić. A detailed analysis of the temporal changes (aging) of the starch solution was described in this paper. The collaboration with J. R. Katz probably begun in early 1930s, since in 1932 a joint article 29 with M. Samec appeared in the January issue of the Zeitschrift für physikalische Chemie, followed by three further articles in the following years. Richard Klemen not only worked as a university teacher. In 1939 he co-authored two textbooks 30,31 on mineralogy and chemistry for secondary schools (3 rd and 4 th grade) together with Vladimir Žitko, another former student of Maks Samec initially working on starch chemistry who later taught chemistry at various grammar schools in Slovenia and Croatia. In addition, in 1940 he wrote an article 32 on chemistry of fertilization for the Slovenian popular science magazine Proteus. In this article Klemen described the activity of extremely highly diluted saffron crocin-type molecules onto gamete mating in green algae as previously reported by Kuhn and co-workers 33 .

Emigration and Early Career in Vienna
With the death of Richard's father in 1936, his land in Konjice was inherited by Richard. As assistant professor he was not able to be personally involved in grapevine cultivation and wine production. Instead, in their Konjice house lived two families of vintners who worked in the Klemen vineyards 34 . In April 1941 World War II began in Yugoslavia. The Slovenian territory was divided between Italy, Germany and Hungary. The Province of Ljubljana was integrated into the Kingdom of Italy and the work at the university was significantly impeded 35 .
For the winter semester 1941/42, which ended on 15 February, Richard Klemen was still listed as a lecturer, but he received permission from the Italian provincial authorities to quit his position at the UL and emigrate to Germany after 31 January 1942. His enzymology course was later appointed to honorary lecturer Marta Blinc, who was advertised for the summer semester 1942/43 as lecturer for the course Selected Topics in Biochemistry and Enzymology (Slov.: Izbrana poglavja iz biokemije in enzimologije). Strangely enough, Richard Klemen still appeared in the course catalogue 19 for the winter semester 1942/43, which indicates that these lists are to be regarded as a historical source with care.
It could only be speculated about the reasons for Klemen's decision to leave the Italy-occupied Ljubljana, but there were probably several of them: German language ties, family property in the north of the country, which were now part of the German Reich, constantly growing teaching duties (reflected in the number of courses he delivered, see Table 1), rumours that resistance troops were hostile to people of German origin, and perhaps the fact that he appeared on the list of Kočevje Germans to be moved from the Kočevje area 36 to the plains along the Sava river on the then German side of the border to the Slovenian territories occupied by Italy. In this exodus almost all members (about 12,000, i.e. 95%) of the German minority left their villages 37 . The inability to conduct competitive research under Italian occupation in Ljubljana could also be important. The difference between the highly produc-tive years of 1938-9 and the war situation must have been considerable. At that time Austria seemed isolated from war activities and thus offered itself as a comfortable refuge with perspectives for further research in the field of chemistry. Last but not least, Vienna was regarded as the centre of chemical education and he might have used some connections to colleagues of his former mentor, Maks Samec.
It seems obvious that Klemen's emigration to Germany (actually Austria, which was annexed to Germany in 1938) was well planned, as he was already working as a research assistant at the Vienna College of Technology on April 1, 1942. He was a member of the Institute of Inorganic and Analytical Chemistry led by Ulrich Hofmann and later by Robert Strebinger.
Essentially from the wartime comes Klemen's research, which was published only in 1950 in Zeitschrift für anorganische Chemie 38 with double authorship of Ulrich Hofmann and Richard Klemen. This is certainly the most frequently cited work of Richard Klemen. It describes an important observation in clay chemistry that is still referred to as the Hofmann-Klemen Effect. Ulrich Hofmann (1903Hofmann ( -1986) is a well-known German chemist who (between 1942 and 1945) headed the institute in Vienna, where Klemen began as a research assistant after leaving Ljubljana. Hofmann's earlier position was that of a university professor in Rostock, Germany, from where he received one of the then rare and valuable electronic microscopes. In addition to basic research, he conducted several military projects 39 . Due to his involvement in German army-linked research and his membership in the paramilitary SA (Sturmabteilung) forces where he hold the title of Scharführer 40 , he had to leave Austria in 1945. Since it was not possible for him to work in an exposed position after the war, he was first engaged as a gardener in a chemical production plant in Bavaria. Then, in 1948, he was asked to establish chemistry courses at the Regensburg university (then Philosophisch-Theologische Hochschule), where he first had to set up laboratories and start up courses 41 . For this reason, Klemen's research was probably published only in 1950 and with affiliation to the Regensburg university. However, Klemen remained bound to Vienna College of Technology and belonged to the minority of researchers who were not removed from their positions during the socalled "denazification" in post-war Austria. Only 35% of the researchers were allowed to remain 42 .
In their 1950 paper, Hofmann and Klemen presented results that had already been achieved in Vienna in 1944 41 . Experimental data indicated that in clay (bentonite, more precisely montmorillonite) suspension with lithium, swelling and cation exchange capacity were lost when heated to 125°C. The proposed explanation was that lithium ions diffused into the octahedral sheet of the montmorillonite layer. This effect was later studied by several authors and the 1950 paper is still occasionally quoted. Klemen (1861-1927) was an Austrian chemist, professor of organic and technical chemistry, associated with the Vienna College of Technology. He investigated natural compounds which is a connecting point to Klemen's interest. In addition, Bamberger was supervisor of the doctoral thesis of Margarete Garzuly (1923), who later married Alexander Janke, head of the Institute of Biochemical Technology and Microbiology 44 . One can imagine that A. Janke was originally supposed to write the text, but either because of his illness or perhaps because of a conflict of interest, the biography was finally prepared by Klemen.
The list of publications from Klemen's Vienna period is unexpectedly short, which is likely due to the fact that he was not in the role of project leader but rather assisted in various research and applied projects. Nevertheless, he was co-author of some of the publications in the field of food technology. In 1957, together with Alexander Janke he published a professional paper on the biological stabilization of grape juice with an ion-exchange resin 45 . Two years later, together with E. Seitz, he published an article on paper chromatographic analysis of the Maillard reaction 46 . This paper was dedicated to Professor Janke on the occasion of his 70 th birthday.

Klemen's Late Career in Vienna
In April 1964 Richard Klemen was appointed "Titular Associate Professor", which is an honorary professional title in Austria. In 1967 he retired from the Vienna College of Technology, but continued to teach at the University of Agriculture in Vienna (BOKU), from 1966 as an external lecturer. He was in charge of the course on operational and quality control (Ger.: Betriebs-und Qualitätskontrolle), appointed to the Institute of Food Technology and Chair (Ger.: Lehrkanzel) of Biochemical Technology. In 1964, Klemen was actually among the candidates for the head of the newly founded BOKU's Institute of Food Technology as the second choice after Hans Klaushofer, who was later appointed to this office 47 .
The appointment of Klemen to BOKU coincided with the retirement of Professor Armin von Szilvinyi in 1966. Interestingly, von Szilvinyi held two positions: he was head of the Institute of Biochemical Technology and Microbiology (where Klemen was employed from 1950 to 1967) at the Vienna College of Technology and professor at the Chair for Applied Biochemistry and Microbiological Research Methods at BOKU, where Klemen from 1966 was finally offered the opportunity to give his own lectures.
In each semester Klemen gave 3 h lectures per week, while the practical course was not under his direct supervision. In the academic year 1976/77 this course was taken over by Helmut Zenz, the later head of the Institute of Food Technology. In parallel to his assignments at the BOKU, Klemen also worked with the Experimental Station for Fermentation Professionals (Ger.: Experimentalstation für Gärungsgewerbe) 48 which was closely associated with BOKU 47 , but later developed into an independent school for professional education. From his late career, Klemen's contribution at a seminar on sensory analysis in milk production was published 49 .
On the occasion of his 85 th birthday, Alfred Lechner, head of archives at TU Wien, assembled a curriculum vitae 50 summarizing Richard Klemen's achievements. This summary was an important source of information for the present article.

Richard Klemen's Private Life
In his young years, especially when he attended schools with German as language of instruction, Klemen's first name was written with a 'ch' (Richard), while as student and until 1942 his first name was written with an 'h' only (Rihard). After his move to Austria he adopted the German form of his first name again.
During the outbreak of World War II in Yugoslavia in April 1941, Richard Klemen was mobilized to Serbia where he was captured by German troops and sent as a prisoner to Essen, Germany. After several weeks of imprisonment a , he was allowed to return to Ljubljana, where he continued his work at the university.
Richard's mother (aged 82) and his younger brother Toussaint and his family were part of the 1942 organized Gottscheer move from their home villages to the German-occupied lowlands along the Sava River, from which the local population had previously been expelled. Toussaint worked on a farm, but after partisans attacked the area he decided to move to Konjice. There, Richard's mother died in 1943. Toussaint and his family were expelled 51 to Austria in January 1946. They initially lived as war refugees in Austria, but later settled in Germany. a UL archives keep a letter from the Italian chemical supplier Eigenmann e Veronelli dated 3 July 1941, which was replied in written on 12 July 1941. The Italian company inquired about the current address of Richard Klemen. UL rectorate replied as follows: »We have the honour to inform you that Dr. Richard Klemen is prisoner of war in Germany«.
After Richard Klemen obtained his research assistant position in Vienna in 1942, he refused to join the National Socialist German Lecturers League (Ger.: Nationalsozialis-tischerDeutscher Dozentenbund), a division of the Nazi Party. This could be the reason why he was not allowed to work as a lecturer, which was his previous position at the University of Ljubljana. It is known that until 1945 the 'Lecturers League' was giving opinion about all candidates for teaching positions at German (and also Austrian) universities 52 .
After World War II Richard Klemen was visited several times by strangers, who inquired about his possible return to Yugoslavia. On 34 . Attempts by the family to recover possession of the confiscated property were unsuccessful. Richard Klemen died on 19 May 1998 at the age of 96. He is buried in Vienna Central Cemetery. He is survived by his son Ulrich, who studied medicine and specialized in ophthalmology. He became chief physician and associate professor of ophthalmology. His wife Christine is also an ophthalmologist.

Bibliography
English translations of original titles are in square brackets. Richard Klemen as (co-)author is underlined in all entries.