103 



who had had only two years of practical experience in the micro- 

 biological field ! 



Undoubtedly encouraged by the sensation which these papers 

 caused amongst botanists and agriculturists, Beijerinck unfolded an 

 astonishingproductivityinthe years which foliowed. And again, it is 

 most surprising to see that a man who was charged with control and 

 research work in order to promote technical yeast production, was 

 able to spare the energy and time necessary for the solution of several 

 problems of a purely scientific character. It is true that in this con- 

 nection the very liberal attitude assumed by the management of the 

 "Nederlandsche Gist- en Spiritusfabriek" cannot be too highly praised. 

 But at the other hand it is quite certain that Beijerinck did not 

 escape being involved in the numerous troubles inherent in the pro- 

 duction of yeast on a technical scale. So for instance in a memorial 

 book entitled "A pilgrimage into yeastland", published by the yeast 

 factory in 1893, we find interesting data regarding the work done by 

 Beijerinck to oppose the alarming rumours that pressed yeast 

 could act as a carrier of cholera germs. Besides much experimental 

 work, Beijerinck's campaign included several visits to leading 

 bacteriologists and hygienists in England. 



Notwithstanding all that, the scientific achievements of Beijerinck 

 in his "industrial period" were manifold, and amongst them were 

 several first-rank contributions. We will mention here only his three 

 fundamental papers on the physiology of luminous bacteria, the first 

 and successful application of microbiological methods in the study 

 of unicellular green algae, zoochlorellae and gonidia of lichens — 

 leading to pure cultures of these organisms — his discovery of the 

 remarkable yeast species Schizosaccharomyces octosporus, his studies 

 on the butyl alcohol fermentation, those on the micro-organisms of 

 kefir, and on the enzyme lactase, etc. 



Moreover, extensive investigations were made on the nutritional 

 requirements of various micro-organisms and new methods for this 

 study were developed, so for instance the so-called "auxanographic 

 method". 



Yet there is no doubt that Beijerinck's removal in 1895 to more 

 academie surroundings was ultimately feit by him as a liberation. 

 Here, in the new laboratory built according to his own design, sec- 

 onded by assistants like van Delden, van Iterson, Jacobsen and 

 Söhngen, conditions for a further development of the microbiologist 

 were almost optimal. 



The characteristic feature of the first three years after the opening 

 of the "Bacteriological Laboratory of the Polytechnical School" in 

 1897 is that Beijerinck had a strong inclination to return to the 

 subjects which had had his interest in the Wageningen period. This 

 manifested itself in an extensive paper on galls, in the publication on 

 mosaic disease in tobacco — which may be considered to mark the 



