43° BOTANICAL GAZETTE [JUNE 
Fig. 1g. A definite wall separating the spore into two approximately equal 
parts. 
Fig. 20. Same as preceding, but one part showing what may be interpreted . 
as a generative nucleus and a tube nucleus. 
ete 
THE DIVISION OF THE MACROSPORE NUCLEUS. 
Joun H. SCHAFFNER 
(WITH PLATES XXXVII-XXXIX) 
Although a knowledge of the changes which take place in 
the reduction nuclei of plants and animals is of the utmost 
importance, and will no doubt aid more than anything else in 
bringing about a correct interpretation of the facts of heredity, 
comparatively little has been done in this field, and the observa- 
tions that have been reported disagree widely. This may be 
accounted for because of the extreme difficulty of properly pre- 
paring suitable material for study, and of correct observation 
and interpretation of the minute structures concerned. The 
following work was undertaken because especially favorable 
material was at hand, and some peculiar variations from what 
has been received as the normal process of reduction were 
observed. During the course of the investigation the writer 
was compelled several times to abandon preconceived notions 
obtained from the literature of the subject. Whatever, there- 
fore, is presented in regard to the formation of chromosomes 
ae and the activities of the nucleoli during karyokinesis has not 
- been the outcome of an attempt to establish evidence which 
ae would be agreeable to some hypothesis, but the whole investi- 
a ation presented an array of facts conclusive to the writer's 
