362 Mr. Blackman and Miss Fraser. Sexuality and [Oct. 31, 



at a definite point in the life-cycle, and replace in phytogeny the ordinary 

 sexual process, it seems proper that their relations should be exhibited in 

 the terminology, and they should be classed as sexual processes or fertiliza- 

 tions, with the addition of the term " reduced," which indicates that one, 

 or both, of the regular sexual cells has been replaced by some other cell. 

 In the case of Phragmidium violaceum* and the " apogamous " prothallia, 

 we may consider that there has been a sudden return in part, or as a whole, 

 to the primitive condition where every vegetative (gametophytic) cell is a 

 gamete. 



It appears, then, from the study of H. granulata that the female 

 ccenogamete possesses a very striking property — the capacity to fertilize itself. 

 It may be that in this capacity lies the explanation of the development 

 without male sexual organs which seems normal for a large number of 

 Ascomycetes ; future research can alone settle this point. 



Although the sexual process to be observed in H. granulata is, of course, 

 morphologically reduced in relation to the normal sexual process, yet 

 physiologically there can be little to choose between the fusion of ascogonial 

 nuclei, which may be separated in descent by many divisions, and the 

 ordinary sexual fusion in which, as is often the case, the antberidum and 

 ascogonium are intimately related in origin. In fact the kinship of the 

 fusing nuclei may very likely be closer in Boudiera, where sexual organs 

 are borne in pairs on the same hypha and contain a small number of nuclei, 

 than in Humaria, where the number of nuclei in the ascogonium is very great.f 

 As has been suggested elsewhere (Blackman (6)), the majority of the 

 (morphologically) normal sexual fusions in the Fungi, exhibiting as they do 

 close-related sexual organs, are already physiologically reduced in relation 

 to the typical (and probably primitive) exogamic sexual process. The 

 morphological reduction found in the special fusions is thus only a small 

 step which does not affect the physiological nature. In other words, 

 instead of the fusion of the gametes from two gametangia borne close 

 together and in intimate relation on the same plant, we have the abortion 

 of the one and the fusion in pairs of the gametes of the other ; put in this 



* The case of the eecidium of another species, P. speciosum, in which neighbouring 

 cells fuse in pairs, described by Christman (8), and considered by him as a simple process 

 of conjugation of undifferentiated gametes, would seem to be much better interpreted as 

 a reduced sexual process, in which, in the absence of the male cells (spermatia), the 

 female gametes fuse in pairs, as in H. granulata {vide 7a). 



+ It is not asserted that the close kinship or otherwise of the fusing nuclei necessarily 

 makes any physiological difference, but that judged by this standard the processes are 

 essentially similar ; and it is not clear that there are any other physiological factors 

 which would differentiate the two processes. 



