THE WANDERING TAPETAL NUCLEI OF ARISAEMA 465 
between the cells of the anther wall, whose cellulose stained readily 
and strongly, and the tapetal cells whose walls were but Hghtly stained 
if at all. 
The conditions and phenomena connected with the tapetum m 
the two species of Arisaema were found to be almost identical, so this 
report is made with primary reference to A . triphyllum. The drawmgs 
have all been made from preparations of material of that species. 
Fig. 5. A small portion of an anther cavity showing various forms of tapetal 
nuclei, TN, among developing pollen spores, S. X 1400. 
These have been carefully checked and the development of the micro- 
spores has been carefully compared with material of A. Dracontium. 
The photomicrographs in plate XX were taken from preparations of 
the latter species. 
A section of an anther, made just before the beginning of the 
heterotypic division of the pollen mother-cell nuclei, shows its wall 
composed of a single layer of epidermal cells, and, in its thinnest part, 
a single row of sterile cells which later elongate radially and become 
thick walled. Within these two tissues there is a third, the tapetum, 
from two to four cells thick. The drawings have been made from 
portions of sections which show clearly the relation of the tapetum to 
