376 Wisconsin Academy of Sciences, Arts, and Letters. 
7. The nuclei in process of division in the embryonic sporangio- 
spores reverse their progress and the portions reassemble to form 
the nuclei of the mature spores. 
8. Upon germination of the zygospores of Phycomyces nitens the 
reserve material in the nuclear vacuoles contributes to the forma¬ 
tion of slimy cytoplasm. There is no evidence of nuclear division 
in the germ tube or in the zygospore. 
9. Upon the resumption of growth of mycelium, the reserve of 
the nuclear vacuoles contributes to the formation of new cytoplasm, 
as do the similar structures of the germinating zygospores. 
Sincere thanks are due Prof. E. M. Gilbert for his stimulating 
and encouraging interest and suggestions while this work was being 
carried on. 
Department of Botany, 
University of Wisconsin 
BIBLIOGEAPHY 
Burgelf, H. (1915). Ilntersuchungeii iiber Variabilitat, Sexualitat und 
Erblichkeit bei Phycomcyes nitens Kunze. Flora 108:353-448. 
-(1920). XJeber den Parasitismus des Chaetoeladium und die hetero- 
caryotishe Natur der von ibm auf Mucorineen erzeugten Gallon. Zeits- 
chrift fur. Bot. 12: 1-35. 
Dangeard, P.-A. (1903). Les ancetres des Champignons su6rieurs. Bot- 
aniste 9: 227-252. 
Dangeard, P.-A., and Leger, M. (1894 a). Eecherches sur la structure des 
Muconin^es. Botantiste 4: 4-11. 
-(1894 b). Eecherches sur la structure des Muconinees. Compt. Eend. 
Acad. Sci. Paris 18: 430-432. 
Gruber, E. (1901). Ueber das Verhalten der Zellkerne in den Zygosporen 
van Sporodinia grandis Link. Ber. Deutsch. Bot. Ges. 19: 51-55. 
-(1912). Einige Beobachtungen iiber den Befruchtungsvorgang bei 
Zygorynchus Moelleri Vuill. Ber. Deutsch. Bot. Ges. 30: 126-133. 
Haider, E. A, 1899). Cell division in sporangia and asci. ^ Annales Bot. 
13: 490-503. 
Istvanffi, Gy. (1895). Ueber die Eolle der Zellkerne bei der Entwickelung 
der Pilze. Ber. Deutsch. Bot. Ges. 13: 452-467. 
Keene, M. L. (1914). Cytological studies of the zgospores of Sporodinia 
grandis. Annales Bot. 28: 455-470. 
-(1915). Studies of zygospore formation in Phycomcyes nitens Kunze. 
Trans. Wis. Acad. Sci., Arts, Letters 19: 1195-1220. 
Leger, M. (1895 a). Structure et developpement de la zygospore du 
Sporodinia grandis. Rev. Gen. Bot. 7: 481-496. 
-(1895 b). Eecherches histologiques sur le developpement des Muco- 
rinees. Compt. Eend. Acad. Sci. Paris 120: 647-649. 
