25 



reduction, following up BEIJERINCK'S earlier investigations, in which 

 he had assisted (Cf . Appendix C) . 



VAN DELDEN was a very modest and unselfish person, and was 

 devoted to the man who had done so much to widen his scientific 

 horizon. 



In 1902 BEIJERINCK obtained a second assistant on his staff. He 

 was, moreover, so fortunate as to find a very competent candidate. 

 Struck by the exceptionally fine way in which G. VAN ITERSON Jr. 

 had taken his final degree, he invited this young scientist to become 

 his collaborator. After some hesitation, VAN ITERSON - -who until that 

 time had been specializing in physical chemistry - - accepted the in- 

 vitation. There is no doubt that VAN ITERSON is by far the most bril- 

 liant pupil BEIJERINCK ever had. VAN ITERSON quickly exhibited 

 great activity, and his independence being apparently a match for 

 BEIJERINCK'S, he laid down the results of his investigations in several 

 publications under his own name (Cf. Appendix C). His studies on 

 denitrification and on the aerobic decomposition of cellulose have 

 proved to be of a fundamental nature. Gradually his interest shifted 

 more and more to the field of general botany. His Doctorate thesis, 

 entitled "Mathematische und mikroskopisch-anatomische Studien 

 iiber Blattstellungen", bears witness to his remarkable achievements 

 in this field. That BEIJERINCK had a great admiration for the scientif- 

 ic capacities of his collaborator may be judged from the way in which 

 he once introduced VAN ITERSON to the then Minister of Home Affairs, 

 Dr. A. KUYPER, who paid a visit to his laboratory. BEIJERINCK said 

 on this occasion: "This is Mr. VAN ITERSON, my assistant, who knows 

 much more than I do". 



VAN ITERSON'S scientific evolution soon made it clear to BEIJE- 

 RINCK that his assistant was the right man to accept responsibility 

 for part of the teaching. To begin with, he made VAN ITERSON organize 

 a special course on plant anatomy, but it soon became apparent that 

 this part of the curriculum of the chemistry students would be able to 

 flourish only, if more material support could be provided. Therefore, 

 shortly after VAN ITERSON had taken his Doctor's degree, a new chair 

 of "technical botany" was created for him, and he was thereupon 

 moved to a new laboratory especially equipped for the study of pure 

 and applied botany. 



A third assistant, one whose activities have undoubtedly been of 

 great significance for the development of BEIJERINCK'S work, is 

 H. C. JACOBSEN. He succeeded VAN DELDEN in 1904, and holds the 

 record for length of service, for he did not leave the laboratory until 

 1916. He then became bacteriologist to the Jurgens Margarine Works, 

 later amalgamated into the Unilever concern. 



The articles which JACOBSEN published in his Delft period under 

 his own name can be found in Appendix C. Amongst them, his in- 

 vestigations on the unicellular alga Haematococcus pkivialis, and on 



