1899 | LIFE-HISTORY OF LEMNA MINOR 51 
The number of microspore mother cells formed is as large as 
would be expected in a loculus of this size. A striking fact, 
however, is that comparatively few of them develop spores, since 
23 
1G, 21. Spore mother cells with distinct chromatin bands in nuclei, and irregular 
masses of cytoplasm about them ; some tapetal cells divided. 1375. 
Fic. 22. Part of loculus; mother cells with divided tapetal cells. X 1375. 
Fic. 23. Loculus with spore mother cells dividing; one tapetal cell has elon- 
gated very greatly, its nucleus having divided. X 1375. 
many disorganize, and together with the tapetum nourish the 
remaining mother cells (figs. 24, 25). These broken down 
mother cells frequently form incomplete chains extending into 
and almost across the loculus, though such masses are usually 
found near the tapetum. They react to stains as the tapetum, 
and doubtless assume the function of the latter as nutritive 
tissue. Similar conditions are well known in Salvinia and 
Azolla, where disintegrating mother cells gather about the 
remaining ones and nourish them. In Li/ea subulata (18), also, 
there are certain cells between the sporogenous tissue and the 
tapetum which seem to represent those just described. 
Each functioning mother cell gives rise to four microspores 
by first dividing into two divisions, each of these again dividing 
by spindles in the same plane as the first, but with their longi- 
