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



preliminary to fusion. In a number of cases, however, nuclei were found in 

 pairs more or less isolated from their fellows, which were probably to be 

 considered as on the point of fusion. The actual fusion of nuclei seems to 

 take place very quickly, for such a stage as that of fig. 14 is rarely seen, but 

 the nucleoli apparently remain for some time separate, for the nucleus with 

 two nucleoli (figs. 15, 16, 17) is found more frequently. Apart from the 

 stages of contact, which must necessarily be impossible to distinguish with 

 certainty, more than 11 cases of actual fusion were observed, so there can 

 be no doubt that the fusion of the ascogonial nuclei in pairs is a regular 

 process. The size of the nuclei is not of much help in deciding whether a 

 given nucleus is or is not the result of fusion, as three or four different sizes 

 of nuclei may be observed in a single ascogonium (fig. 18). The nuclei 

 apparently undergo a fairly rapid growth in size, those at the centre of the 

 ascogonium being usually smaller, at least in the later stages, than those at 

 the periphery. 



The number of nuclei in the ascogonium varies apparently with the size 

 of that structure, but in order to gain some idea of the number in an average 

 ascogonium the nuclei were counted in two cases in a series of sections of an 

 ascogonium. In the young ascogonium, of which a section is shown in fig. 7, 

 the number 336 was determined, while the older one of fig. 10 gave 824. 

 These countings are, of course, only approximate, as the nuclei are very 

 crowded, and lie sometimes one above the other ; also in the older asco- 

 gonium, a small number of the nuclei had already migrated, and some of 

 those still remaining had, no doubt, already fused. The number produced by 

 the division of the original nuclei of the ascogonium might therefore be taken 

 as about 1000. ISTo data were obtained as to the number of nuclei in the 

 ascogonium at its first inception, but judging from the size of the organ at 

 that stage and from the relatively small number of nuclei in the vegetative 

 cells, very numerous divisions must take place. It is curious that such 

 divisions were never observed in the ascogonium ; it is probable that they 

 are intermittent in occurrence ; possibly they take place only at night. 



When the nuclei pass out into the ascogenous hyphse they show a very 

 distinct nucleolus and are easily defined structures (fig. 11); thus the distinc- 

 tion of the ascogenous from the vegetative hyphse (fig. 19) among which 

 they ramify is rendered possible. 



The ascogonium becomes finally emptied of its contents, though sometimes 

 a few nuclei and a little cytoplasm remain behind at the periphery. Soon 

 after the ascogonium becomes empty, the connection of the ascogenous hyphae 

 with it becomes obliterated, and these hyphse appear as independent struc- 

 tures. This result is no doubt brought about by the pressure of the 



