RIDDLE. —ON THE CYTOLOGY OF THE ENTOMOPHTHORACEAE. 181 



more and more of the safranin, so that the larger granules show a 

 decided red. These granules then become aggregated into a definite 

 number of spherical chromosomes (Figures 2-6). The organization of 

 the chromosomes thus appears due to the direct aggregation of the 

 granules, no spireme stage having been observed. 



During this process of aggregation the nucleolus has taken up a 

 position near the centre of the nucleus ; but with the formation of the 

 chromosomes the nucleolus is no longer distinguishable, since it is 

 identical in size, shape, and staining, with the chromosomes. There 

 is also no difference in behavior during the later stages of division. 

 It must therefore be concluded that the so-called nucleolus of Ento- 

 mophthora is in reality a chromatin-nucleolus, or karyosome. This 

 karyosome does not contain, however, all the chromatin-content of the 

 nucleus, as has been described by Wolfe (:04) for Nemalion, and by 

 Mitzkewitsch ('98) for Spirogyra ; on the contrary, it is equivalent to 

 a single chromosome. The total number of chromosomes in the 

 nucleus of E. Americaim (including this "nucleolar chromosome") 

 appears to be eight. This was seen clearly in many cases, and is 

 illustrated by Figure 6 and by the lower daughter-nucleus in Figure 8. 

 "VVe have apparently in this species a condition where one of the 

 chromosomes persists during the resting-stage of the nucleus as a 

 chromatin -nucleolus. The writer has been unable to find anything 

 comparable to this described for plants, but among animals Montgomery 

 ('98) has described a similar condition in the spermatogenesis of 

 Pentatoma. 



The organization of the spindle in Entomophthora shows interesting 

 conditions. It is always intranuclear and develops in the following 

 manner. As the chromatin-granules draw toward the central region of 

 the nucleus, they leave evident in the outer clear zone, numerous 

 linin-fibres radiating in all directions from the central aggregation of 

 chromatin (Figure 4) and running to the wall of the nucleus, which 

 persists through all stages up to the telophase. It is highly probable 

 that the chromatin-granules were, in the resting-period, distributed 

 along these linin-fibres, which become evident, however, only when the 

 granules draw toward the centre. The linin-fibres would thus be 

 attached to the chromosomes by their proximal ends. The fibres, at 

 first radiating in all directions, tend to separate into two groups, which 

 gradually migrate toward the respective poles of the now somewhat 

 drawn-out nucleus (Figure 5). These fibres form the spindle of the 

 mitotic figure, which is thus derived wholly from the linin, and is 

 therefore strictly intranuclear in origin and position (Figure 7). In- 

 tranuclear spindles have been described for a large number of plants 



