140 BOTANICAL GAZETTE [auGust 
one which is formed early and which disappears early, leaving only a 
few thin layers, called “tapetum” by LANG (3) and not explained. 
In fig. 22 this encroachment upon the “spongy tissue” has gone 
on until only about three or four rows are left between the sac and 
the bounding narrow cells (c). These inner cells have enlarged 
many times, as is shown by the magnification of the figures recorded. 
The walls of these cells (b) have become quite thick, the cells are full 
Fic. 22.—Detail of embryo sac with many free nuclei; diminished “sp 
tissue”; cells of tissue (6) have increased in size and assumed nutritive func 
¢, flattened cells. x 580. : 
of cytoplasm, and the nuclei are not large, though not disorganizet 
The sac has now a broad cytoplasmic layer and a heavy wall. 
nuclei are scattered everywhere, but have no walls as yet; at I 
none were seen in a careful examination with a +, oil immersion 
The membrane is drawn away from the “spongy tissue” for a li 
' distance at the micropylar end, so that in cutting the ovule it loos’ 
if this end of the sac was not filled in | 
From this stage on, the history of the development of the sac 3 
been fully worked out in other forms by Warmrnc (6), whose — 
tion of the endosperm formation is excellent, by IkENO (7), and 
others, so that it did not seem worth while to examine later mé 
at least not until the gaps behind could be closed up. 
