378 Wisconsin Academy of Sciences^ Arts^ and Letters, 
Fig. 12. Embryonie spore. Nuclear division arrested in progress at about 
this stage. 
Figs. 12a and 12b. Stages in the maturation of spores, and shrinking of 
nuclear vacuoles. 
Figs. 13a and 13b. Showing nuclear vacuoles becoming filled with reserve 
material in a zygospore. 
Fig. 13c. Four sister nuclei from zygospore; one is enlarged somewhat 
by a vacuole within, and is becoming filled with reserve material. 
Figs. 14a and 14b. Nuclear vacuoles filled with reserve material, from aged 
hyphae. 
Figs. 15a and 15b. Nuclei from hypha propogated from aged mycelium. 
In 15a slimy cytoplasm is forming around the nuclear structure; in 15b the 
reserve material has been dissolved. 
Fig. 16. Aged hypha after 16 hours on culture medium, after its protoplasm 
has renewed activity. 
