107 



weinig gevallen zijn de gallen nauwkeuriger, de daartoe behoorende 

 parasieten minder goed bekend : dit is het geval met de wortelknolle- 

 tjes der Papilionaceeën" i). Taking into consideration Beijerinck's 

 unquenchable thirst for knowledge, it seems probable that during his 

 work at the Agricultural College in Wageningen he would not have 

 lost sight of the problem in question. One might even expect that 

 thus early he would have made various efforts to solve the riddle. Yet 

 no evidence in favour of this view is available 2), and in any case it 

 appears certain that in his agricultural period Beijerinck made no 

 significant advance towards the solution of the question. For we have 

 already seen that at that time Beijerinck was not yet a microbiolo- 

 gist, and that certainly he lacked bacteriological experience. 



In view of all this, it is most surprising that Beijerinck after two 

 years of an industrial career, working in the unfavourable surround- 

 ings of the Delft laboratory, suddenly decided to devote a good deal of 

 his time and energy to the subject of root-nodule formation. 



Still it is tempting to give some explanation for this unexpected 

 behaviour. The year bef ore, Hellriegel 3) had published the results 

 of his fundamental investigations w^hich brought convincing proof 

 that the Leguminosae possess the exceptional quality of fixing at- 

 mospheric nitrogen, but that for that end it is necessary for special 

 bacteria to enter into a symbiotic relationship with the plant, which 

 event then leads to the formation of the root nodules. However, Hell- 

 riegel's papers were published in periodicals which were not readily 

 accessible, and Beijerinck's attention may well have been drawn to 

 them only by an abstract which appeared in the 1887 volume of the 

 "Centralblatt für Bakteriologie und Parasitenkunde" *). The para- 

 mount importance of Hellriegel's discovery must certainly have 

 made a great impression on Beijerinck's susceptible mind. Beije- 

 rinck must have feit at once that owing to his newly gained bac- 

 teriological experience he was predestined to the task of isolating the 

 as yet unknown causative organism, thus completing the experiment- 

 al proof of Hellriegel's startling discovery. The scientific passion 

 aroused by this idea made him almost forget that he formed part of 

 an industrial concern, and that it was his task to supervise yeast pro- 

 duction. Nor did he evidently pay any attention to the unfavourable 

 conditions under which the work had to be performed. 



1) Translation: "Only in a few examples are the galls better known than the para- 

 sites; such is, however, the case with the root nodules of the papilionaceous plants". 



2) Professor Adolf Mayer, who was intimately connected with Beijerinck 

 during the latter's stay in Wageningen, has kindly informed me on my request that 

 he deemed it quite possible that Beijerinck already did some experimental work 

 there on the causative organisms of the root nodulus, 'but that he (A. M.) was unable 

 to find any positive indications in favour of this assumption. 



3) H. Hellriegel, Tageblatt der 59 Versammlung Deutscher Naturforscher und 

 Arzte in Berlin, 1886, p. 290; Zeitschr. Ver. Rübenzucker-Industrie deutschen Reichs, 

 36,863, 1886. 



*) Centralbl. f. Bakt. u. Parasitenk. 1, 133, 1887. 



