546 Scientific Proceedings, Royal Duhlin Society. 



end contained witliin the antheridium and passing out at or near the base of 

 the latter to join the hypha which bears it, and which is in close proximity 

 to, but has only a very distant anatomical connection with the hypha which 

 bears the antheridium. Figure 10, Plate XLIII, is reproduced from a 

 photomicrograph of the sexual organs taken just prior to the formation of 

 the oosphere. 



This method of development of an apparently sexually formed spore by 

 the penetration of the male organ by the female — the reverse of what is 

 usually the case — is as far as I can ascertain something quite unique among 

 the fungi. The cytological aspects of the question have not yet been studied, 

 but it is hoped to do this immediately. 



(c) Conidia. — During the examination of cultures in Petri dishes, on 

 slants in test-tubes or on cover-glass films, conidia were seen extremely 

 rarely, and in the few cases where isolated examples were observed they did 

 not appear to come to maturity. They were formed perhaps most frequently 

 in the case of cover-glass film cultures when the mycelium had grown beyond 

 the limits of the film, and the lips of some of the hyphae had come into 

 contact with minute drops of water which had condensed on the cover-slip. 

 Even here, however, the development was not good, and the conidia either 

 frequently burst and lost their contents {not in the form of zoospores) or 

 continued to grow at their apices, often with considerable branching at these 

 points, into ordinary mycelium. 



As pointed out previously, cultures with a considerable development of 

 aerial mycelium frequently presented the appearance, when looked at with 

 a pocket lens, as if an abundance of conidia was present, but when examined 

 with the microscope the appearance was found to be due to the fact that the 

 tips of the aerial hyphae were merely somewhat swollen, and no conidia 

 were present. 



Conidia were first obtained in abundance when portions of mycelium 

 (generally with small portions of nutritive medium accompanying them) from 

 a pure culture were introduced iuto the sterilized watery extract of a peaty soil. 

 Under these conditions, although there might be little or no further develop- 

 ment of the mycelium in the liquid apparent to the naked eye, yet plenty of 

 conidia were formed. If the amount of medium transferred with the myceKum 

 was considerable, there was a corresponding further development of mycelium 

 in the liquid, and conidia were also found. 



Conidia (as well as oospores) are also produced in varying numbers when 

 small portions of an affected tuber are removed under aseptic precautions, 

 and placed in the same extract, or in sterilized, filtered, natural bog-water, or 

 even in sterilized rain-water. From the trials which have been made, it would 



