229 



can not therefore imagine that the phenomenon observed, is due to 

 a lessened power to gerrriinate. 



Up to now it was not thought that the influence of a former 

 culture médium could be so great and as a resuit, this fact was 

 never considered in experiments. Yet we certamly must do so 

 and we should not descnbe any différences as a new race before 

 a thorough investigation. Only Grezes has, as far as I know, ob- 

 served a similar phenomenon in Aspergillus niger. He found a 

 quantitative différence m the sécrétion of invertase where the 

 conidia had been derived from cultures on saccharose or succinic 

 acid. But in his case there had been at least sixty générations in 

 tbe same culture solution before and in my expenments I hâve 

 seen, that it is not necessary at ail that the same culture médium 

 should be used for a long time before any marked différence can 

 be observed. I found that growing a fungus for two générations 

 on the same culture solution was quite sufficient. It is certainly 

 worth while to compare thèse facts with the observations of miss 

 Westerdijk and van Luyk, who obtained similar results, when 

 working with the spores of Gloeosporium. 



It is very difficult to décide on a def inite line of conduct amongst 

 ail thèse uncertainties ; I decided to inoculate ail my séries with 

 conidia which had been grown on culture solutions of the same 

 composition. Whenever 1 hâve deviated from this course, spécial 

 mention will be made of it. I think that any possible investigators 

 of this question in the future should adopt the same procédure, 

 because only if they do this, they wiU hâve the right to compare 

 their results with mine. 



The very striking différence between my first results and those 

 of Went, made me consider whether possibly the size of the ex- 

 posed surface of the culture solution could influence the physio- 

 logical behaviour of the fungus. Went worked with a surface of 

 24, later 48 squ.c.M., I with 47 squ.c.M. It did net seem very 

 probable that this could cause variations. Yet I performed an 

 expenment; although I did not find the cause for the différences 

 mentioned above, it was not wholly without results. 75 ce. of 



