1899 | LUFE-HISTORY OF LEMNA MINOR 57 
stains soon renders the tapetal cell indistinguishable from the 
nucellar cells about it. 
The primary sporogenous cell seems to develop directly into 
the megaspore, and as such undergoes a long period of rest. 
Meanwhile the integuments push beyond and enclose the nucellus. 
After the megaspore is formed the cells of the unusually small 
nucellus undergo no further divisions. 
GERMINATION OF THE MEGASPORE. 
The enlarging megaspore encroaches upon the nucellus, 
which, as will be seen from the figures, presently consists of a 
Fic. 46. Eight-celled embryo-sac with nucellus capping micropylar end. X 1375- 
Fic. 47. Probably an eight-celled sac. X 1375. 
Fic. 48. Sac with oospore, synergids, primary endosperm nucleus, and antipodals. 
1375. 
few cells which are so arranged as to form a cap to the growing 
megaspore. The sides of the megaspore are bounded by the 
integuments, and its lower end by the chalazal region of the 
ovule. The nucellus is crowded into the micropyle, and fre- 
quently has some of its cells absorbed by the megaspore, although 
