18 H. MARSHALL WARD. 



development of Meliola, the following points of analogy seem to me 

 sound. The original pyriform branchlet — containing in itself, so to 

 speak, the elements of the fruit-body — after the first division (fig. 9), 

 may be considered as establishing morphologically an archecarpium 1 

 and an anlheridial branch — or the latter may be considered as contain- 

 ing in itself the antheridium, pins the elements of the perithecium wall. 

 If the cells A and B (fig. 9) became further developed, and diverged 

 at their apices, we should have no difficulty in seeing these points of 

 homology. 



Thus much cannot but be allowed. The cell A resembles a true 

 archecarpium in so far that it slowly produces the ascogonium and 

 asci ; the homology will not be weakened, but the contrary, if further 

 research shows that part of the perithecium wall results from cells 

 derived from A. The cell B so far acts as an antheridium branch in 

 that it is closely applied to A, divides up more rapidly, and thus pro- 

 duces most — perhaps all — of the perithecium wall. 



The above may possibly suggest some difficulties to those who have 

 not followed the recent progress in our knowledge of sexual organs 

 and their homologies in the lower fungi. It has of late been shown 

 to be not improbable, but on the contrary very likely, that we should 

 view the Erysiphem as a group connecting the higher Ascomycetes, on 

 the one hand, and the Phycomycetes 2 (Mucor, Peronosporece, and Sapro- 

 legnice) on the other : the evolution of the latter group seems un- 

 doubtedly attended by a fusion of parts before separated — a withdrawal 

 of the sexual organs, so to speak, into one another, — and De Bary has 

 followed this out with marvellous skill and success in a nnmber of 

 forms passing from Pythium, through the Peronosporew, to certain 

 Saprolegnice, in which the male sexual organ (ccntheridium, pollinodium) 

 is normally suppressed. Whether or not we suppose, with De Bary, 

 that the Erysipheoz took origin from some Peronospo7xc-\ike form, it 

 seems reasonable to look upon Meliola and its imme/liate allies as a 

 branch group derived from the Erysiphe stem, either from the ancestor 

 of Erysiphe itself or from ancestors which gave rise to Eurotium and 

 Erysiphe, and that this group has become developed in tropical lands 

 along lines more or less parallel to those along which the European 

 forms have proceeded in temperate climates, being, in fact — though 

 not in the strictest sense perhaps — "representative species." Be this 



1 De Bary, Beitrage IV., proposes to use this word as denoting that part of the body 

 Which becomes the ascus and pedicel in Poiosphaera. 



2 Vide De Bary, " Beitr. z. Morph. u. Phys. d. Pilze," R. IV., 1881. 



