200 PfiYTOPHTHORA PARASITICA. 



after reaching maturity," undergo the same changes, at least out- 

 wardly, as they would have if they had been fertilised. The 

 " resting " conidia germinate readily, while the oospores have 

 not been found till now to germinate, except in one doubtful 

 case. 



Von Faber 1 in Cacao Phytophthora has found oospores but 

 he failed to find antheridia and oogonia. Coleman 2 explains this 

 failure on the ground that the oospores " almost always fill the 

 oogonial cavity so completely that the oogonial wall can be made 

 out only with difficulty." His figures 7, 8, and 9 of Plate XVIII 

 leave doubts in my mind as to their being drawings of true patho- 

 genetic oospores. They seem to be " resting " conidia or chlamydo- 

 spores, which Rorer has found in diseased fruits. They quite 

 resemble " resting " conidia found in Ph. parasitica. 



In the Phytophthora on Hevea brasiliensis, which is considered 

 to be Ph. Faberi by Petch and others, oospores have been 

 found but " Oogonienhaute und Antheridien waren nicht vorhan- 

 den." 3 From spirit specimens of fruit of Hevea brasiliensis 

 attacked by Nectria and by Phytophthora I have come across 

 globular yellow thick -walled (2m thick) bodies, in appearance exactly 

 similar to " resting " conidia found in Ph. parasitica. They measure 

 22 to 30^ in diameter, on an average 27m. These " resting " conidia 

 might have been mistaken as oospores without antheridia and 

 oogonia. 



As in Ph. Pkaseoli*, the antheridium is the first to be 

 found in the development of the sexual organs. The formation of 

 the antheridium is indicated by the terminal swelling of a 

 hypha, which sometimes prolongs its course to a few microns in 

 length beyond the swelling, or by the swelling of the wall of a 



' Von Faber, h\ C. Die PhytopMfwa-F&ule der Kakaofriichte, Arbeiten aus der Kais. 

 Biol. Anst. fur Land-und Forstwirtschaft, VII, 1910, p. 201. 



2 Coleman, L. C. loc. tit., p. 74. 



3 Peters, Uber eine Fruchtfaule von Hevea bnttilicnsis in Karnerun. Ber. lib. d. 

 Tiitigkeit d. Kais. Biol. Anst. im Jahre 1911. Mitt. Kais. Biol. Anst. 1912, No. 12. 



* Clinton, G. P., loc. cit., 1907-1908, p. 902. 



