54<; 



THE AMERICA A NATURALIST [Vol. XLIV 



double division of spore mother cells lias been regarded 

 as opposed to the interpretation of the asens as a spore 

 mother cell. However, as 1 have pointed out, this triple 

 division replacing ordinary double division is to be re- 

 garded as correlated with two nuclear fusions preced- 

 ing it. 



Miss Fraser has brought further interesting cytolog- 

 ical evidence that the third division in the ascus is a 

 reduction division which she characterizes as a brachy- 

 meiosis. The universality of the triple nuclear di- 

 vision in the ascus even in cases where less than eight 

 spores are formed is certainly to be regarded as a fact 

 of the first importance and comparable to the univer- 

 sality with which a double division occurs in other spore 

 mother cells. The most striking of the peculiarities as 

 to cell and nuclear fusions in the fungi may be summar- 

 ized as follows : 



1. The fusion of multinucleated gametes. 



'2. The male element may be a mass of gonoplasm 

 rather than a definitely bounded cell. 



3. Endokaryogamy, the fusion of nuclei not brought 

 together by cell fusion but of more or less independent 



4. The fusion of gametes without the fusion of their 

 nuclei; the latter reproducing by conjugate division for 

 long series of cell generations and finally fusing just 

 before the reduction division. 



5. Fertilization by nuclear migration from a vegeta- 

 tive cell to an egg or fertile cell. 



6. Two successive fusions in the same life cycle, a 

 normal conjugation of gametes and later endokaryo- 

 gamy. 



