RIDDLE. — ON THE CYTOLOGY OF THE ENTOMOPIITIIORACEAE. 191 



When it is recalled that in Eatomophthora gleospora, which, as has 

 been mentioned, Vuiilemin considers typical, the young azygospore, 

 after the formation of the cross-wall, is uni-nucleate, and that the 

 nuclear-divisions and fusions described take place immediately, it will 

 be seen that here, in Empwsa Grylli, we have a very different type 

 of resting-spore formation — a resting-spore multi-nucleate from the 

 beginning and showing neither nuclear-divisions nor nuclear-fusions. 



The evidence seems to indicate that the azygospore of Empusa is 

 more in the nature of a chlamydospore ; and the occasional substitu- 

 tion of an encysted hyphal body, such as is shown in Figure 30, as 

 a means of tiding over the winter period, is in favor of this view. 



Conclusions. 



In conclusion it will be well to consider what light the observations 

 here set forth may throw on the interrelationship of the genera of the 

 Entomophthoraceae, and the relationship of this family to other Phy- 

 comycetes. In comparing the nuclear conditions in the three genera, 

 which have been studied from the cytological point of view, namely 

 Basidiobolus, Entomophthora, and Empusa, two possible lines of de- 

 velopment are offered for consideration. First, it is possible that 

 Basidiobolus, with its uni-nucleate cells, may be a primitive type, from 

 which the development may have proceeded through the conditions 

 seen in the hyphal bodies of Entomophthora, with their several nuclei 

 regularly spaced, to the conditions in Empusa, where the hyphal 

 bodies have a large number of irregularly distributed nuclei. Or, 

 secondly, it is possible that Empusa is the primitive type of a series 

 showing progressive nuclear reduction, which reaches its highest 

 expression in Basidiobolus. 



The first of these two views is supported by Vuiilemin in his paper 

 of 1900. He says: "Au point de vue cytologique, VE. glcospora 

 (ainsi que VE. Delphiland) forme un trait d'union entre les Basidiobo- 

 lus et les Empusa ; il nous montre par quelle gradation la structure 

 cellulaire s'est dans la sdrie des Entomophthordes pour passer ^ la 

 structure multi-nuclde. Cette derni^re apparait alors comme un 

 d(iriv(^ phylog(^ndtique de la premiere : c'est ce qui m'a depuis long- 

 temps sugg^rd I'id^e de la nommer une structure apocytique. Ceci 

 posd, nous interpreterons les vues de Raciborski en disant que la 

 famille des Entomophthordes chevauche sur les ArchimyctJtes et les 

 Phycomycfetes, qu'elle prend ses racines dans le premier groupe au 

 niveau des Basidiobolus, franchit la fronti^re au niveau des En- 

 tomophthora gleospora et Delpiniana pour s'epauouir en pleins Phyco- 



