568 Scientific Proceedings, Royal Dublin Society. 



stated a couple of years previously that he had grown the fungus saprophy- 

 tically, both on gelatine and in liquid media. The two French savants say : 

 " On a deja observe dans la nature le Phytopldhora infestans vivant en 

 saprophyte ; mais a notre connaissance, personne n'est jamais arrive a en 

 obtenir de cultures pures, ni sur le vivant, ni sur les milieux artificiels. Tout 

 ce qu'on sait sur le developpement de cette Peronosporee resulte d'observa- 

 tions faites sur les plantes attaquees ou d'inoculations pratiquees dans les 

 conditions d'aseptie insuffisante." 



It would be interesting to know by whom the fact mentioned by these 

 two sets of authors, and apparently acquiesced in later by Brefeld, that 

 this fungus can grow in nature as a saprophyte, was recorded. We have 

 been unable to find any original statement of this kind ; but if it is a fact 

 (which is doubtful), it might have an important bearing on the question 

 of the recrudescence of the disease year after year. 



In the paper just cited Matruchot and Molliard reported that they had 

 succeeded in cultivating the fungus free from contamination with any other 

 micro-organisms, on pieces of living potato-tubers ; but as to the non-living 

 media on which they obtained pure cultures they are silent. Conidiophores 

 (and presumably conidia) were produced on both kinds of media. 



In a further paper,' published in 1903, these authors reported that they 

 had succeeded in getting pure, conidia-bearing cultures of the fungus on 

 living pieces of the fruits of the vegetable marrow {Cucurhita Pepo) and 

 the Spanish melon (Melon d'Espagne). Pure cultures were also raised on 

 cooked pieces of vegetable marrow, Spanish melon, pear, and turnip, although 

 on the last two the growth was only poor. Conidia were produced on these 

 media or on some of them, but not so abundantly as on the living ones, and 

 their number grew less and less, so that ultimately tlieir production ceased, 

 and the mycelium itself became enfeebled. The fungus also grew on 

 vegetable marrow broth, and produced abundant conidia ; but when this was 

 rendered solid by the addition of agar, fewer of these bodies developed. 

 Appreciable growth was also produced in a three per cent, solution of 

 glucose in water. On none of these media was there any development of 

 sexual spores or of chlamydospores. No growth was obtained on cooked 

 potato, or on cooked tomato and various other fruits and roots. 



Brefeld,- in 1908, gives fuller details of the nutritive solution in which 

 he had found such good growth to take place. It was prepared by cutting 

 young potato-tubers into thin slices, drying them quickly, and then extracting 



' Matruchot, L. et Molliard, M. — Sur le Phytophthora infestans. Annales Myoologici, vol. i, 

 No. 6, 1903, p. 540. 



■ Brefeld, 0., ioc. cit., Baud 14, 190S, p. 41. 



