32 H. MARSHALL WARD. 



At this point we may leave this short survey of Brefeld's important 

 work, and turn to the consideration of a memoir * published by De 

 Bary about the same time as the last one quoted. In this — probably 

 the most important contribution to mycology yet made — the author 

 describes his observations on the Peronosporece and Saprolegnice ; and 

 bases upon these and other previous observations a classification of 

 the fungi which is in large measure new, and certainly promises to be 

 more fruitful than any yet proposed. 



De Bary finds that, passing from the typical Peronosporece (Pythium, 

 &c.) to the Erysiphece on the one hand, and to the Saprolegnice on 

 the other, the sexual process is gradually eliminated, and the sexual 

 organs become at first functionless and the a disappear altogether. In 

 Pythium itself, the antheridium pierces the oogonium wall and ferti- 

 lises the oosphere by pouring protoplasm into it. 2 In Phytophthora 

 and Peronospora the process is essentially similar, but the quantity 

 of protoplasm passed over from the antheridium is smaller. 



In the Saprolegnioe — which differ from Pythium and other Pero- 

 nosp>orece in forming several oospheres in each oogonium — the fertilis- 

 ing tubes do not open, and no protoplasm can be observed to pass 

 over from the antheridium to the oospheres. 3 Or, in some forms, no 

 antheridia are present at all — a fact already recognised by Pringsheim 

 — and the parthenogenetic spores are nevertheless capable of germi- 

 nating. 



Now if the typical and thoroughly investigated case oiPodosphcera^ 

 be compared with the Peronosporece, it is, as De Bary states, evident 

 that the antheridia correspond in both cases; while the "archecarp- 

 ium" [i. e. the cell which produces the ascus, and to which the 

 antheridium applies itself) of Podosphcera is homologous with the 

 oogonium of the Peronosporece. It is a remarkable fact that, as De 

 Bary noticed long ago, 5 the antheridium of Podosphcera only applies 

 itself closely to the archecarpium, and does not pierce it ; it appears 

 highly probable, moreover, that no passage of subs'tance from one to 

 the other takes place — that the ascus, in fact, arises without a sexual 

 process, though the sexual organs are present. 



1 'Beitrage zur Morpli. and Phys. der Pilze, &c.' R. iv, 1881. 

 3 Cf . ' Quart. Journ. Mic. Sc.,' October, 1883. 

 s Cf. also Quart. Journ. Mic. Sc.,' July, 1883. 

 1 De Bary, ■ Beitr. zur Morph. und Phys.,' R. iii< 

 8 De Bary, op< cit. 



