80 N. H. COWDRY. 



certain stages in the spermatogenesis of mammals. But they 

 may be quite uniformly distributed through the cytoplasm or 

 else condensed to one side of the nucleus only. Different spores 

 vary greatly in this respect. Sometimes the spores stain so 

 intensely that the mitochondria can only be distinguished with 

 difficulty. The large clear vacuoles and tortuous spaces which 

 occur in some of the spores indicate that it might be worth while 

 to study this material with methods adapted to the demon- 

 stration of the vacuolar apparatus. The conditions in Badhamia 

 are identical except for the fact that the mitochondria in the 

 spores are much more numerous and filamentous. 



Other alterations accompany the formation of the definitive 

 spore capsules which are best seen in sections of Enteridium 

 rozeanum (Fig. n). The capsules are quite complicated in 

 structure. At first sight they seem to be covered with spines 

 but Fig. ii shows that the spines are in reality the walls of little 

 compartments set upon a homogeneous basement membrane. It 

 often happens that the substance of the spore shrinks away from 

 the membrane. Sometimes this is followed by the partial col- 

 lapse of the membrane itself. The contents of these mature 

 spores are important. The nuclei seem to be much broken down 

 and traces of them can be distinguished only after careful study. 

 The mitochondria have, almost uniformly, reverted to their ori- 

 ginal spherical shape and can easily be stained in the usual way 

 with janus green, if the spore contents are squeezed out in a 

 solution of i : 10,000 of the dye. 



The entire process of spore formation is subject to great 

 variation in different Myxomycetes. In Arcyria denudata, for 

 instance, the process is quite different from that which I have 

 described in Badhamia, Fuligo and Enteridium. The first sign 

 of approaching spore formation is a segregation and encapsulation 

 of comparatively large masses with abundant nuclei and many 

 mitochondria. Instead of being hard to distinguish, the nuclei 

 are quite conspicuous with well-defined chromatin networks and 

 nucleoli. Through successive divisions these multinucleated 

 masses become smaller and smaller. As the final division ap- 

 proaches, the walls become thicker and the nuclei stain less 

 intensely, as is shown in Fig. 12. Division is by mitosis. The 



