1905.] Development of the Ascocarp of Humaria granulata. 363 



way it is clear that there is a morphological difference, but a physiological 

 difference is not easily conceivable. 



When one considers the apparent physiological equivalence of the 

 ordinary and the reduced sexual processes, the ease with which " self- 

 fertilization " can be carried on in the ccenogamete, the small number of 

 forms in which an ordinary sexual process has been observed, and the 

 fairly large number which appear to have no antheridium, it seems not 

 improbable that the reduced sexual process will prove to be the more 

 common type of fertilization in the Ascomycetes. 



It is obvious that the occurrence of fusions among the nuclei of the 

 female ccenogamete itself renders still more difficult the investigation of 

 the sexual cell of this type. The mere presence of a male organ and the 

 observations of nuclear fusions in the female cell is now not sufficient to 

 prove a normal fertilization ; nor even is continuity between male and female 

 organ.'?, for the male nuclei may degenerate in situ, and a reduced fertilization 

 of the H. granulata type may take place. To prove the existence of ordinary 

 fertilization, evidence must be obtained for an actual migration of male 

 elements to the female organ. 



It might perhaps be suggested by some that the nuclear fusion observed 

 by Harper in Pyronema were really fusions between female nuclei like those 

 in H. granulata. Harper's observations on the passage of the male nuclei 

 into the oogonium seem, however, sufficiently satisfactory to allow of this 

 supposition being put on one side. 



Dangeard's observations on Pyronema are very probably to be explained 

 by the supposition that he was working on a form with a functionless 

 antheridium. He worked with artificial cultures, while Harper used natural 

 ones, and it has been shown by Van Tieghem (26), in a paper which seems 

 to have been overlooked in the discussion, that Pyronema is very susceptible 

 to artificial conditions. In his cultures Van Tieghem observed forms which 

 were normal, forms which showed the ascogonium and antheridium reduced 

 in size, and lastly forms in which the antheridium was absent, but the 

 ascogonium developed normally. Dangeard was probably investigating a form 

 in which the antheridium, though still present, had already become function- 

 less ; in the light of the series of forms observed by Van Tieghem, one cannot 

 conclude with Dangeard that the antheridium is always functionless. 



In such a case as Pyronema with a functionless antheridium a " reduced 

 fertilization " similar to H. granulata is to be expected ; such a process 

 would almost certainly be overlooked unless attention was specially directed 

 to it. The other forms lately investigated by Dangeard (10), in which either 

 the antheridium was absent or the male nuclei degenerated, may, perhaps, 



