1885. ] Botany. 7II 
ment of the stoma (Fig. 4), and in the mature stoma the visible 
protoplasm consists merely in a large nucleus in the center of 
each cell (Fig. 6 66). In the mother-cell one or two vacuoles 
may appear in any place, one central vacuole is perhaps the most 
frequent form (Fig. 3), but when division takes place a band of 
thick protoplasm stretches across the center of the cell (Fig. 4 a). 
Instead of condensing this tends to extend through the length of 
the cells leaving vacuoles only in the extreme ends (Fig. 5 a a). 
In the immature stoma this protoplasm is very slightly granular 
and has a slight green tinge, as if chlorophyll is being formed 
(Fig. 5); but in the mature stoma it appears perfectly homoge- 
neous, and small chlorophyll bodies which show the presence of | 
starch on application of iodine, occupy the former vacuoles. A 
cross-section, made before the mother-cell has divided, shows 
very thin walls (Fig. 7), but a section of a mature stoma repre- 
sents the guard cells as having thick walls, and I think it proba- 
ble that most of the protoplasm has been absorbed in the thick- 
ening process (Fig. 8).. This behavior of the protoplasm varies 
some in different stomata, especially in the stages represented in 
Figs. 3 and 4, but the process described prevails, and seems to be 
typical. 
The methods of finding the different stages of development are 
very simple. If the leaves of a growing plant be unrolled until 
the youngest is reached and the base of this used, it will show 
the youngest forms. It is useless to attempt to remove the epi- 
dermis, for the leaves which would contain the undeveloped 
stomata are too tender to permit it. Soaking the young leaves 
in a two per cent salt solution for about ten minutes aids in show- 
ing the formation of the accessory cells, if an examination is 
made immediately.—Zffie A. Southworth, Bot. Lab. Univ. Mich. 
EXPLANATION OF PLATE XXIII. 
Fic. 1.—Mother-cell of stoma. 
“ 2.—Mother-cell and accessory cell. 
“ 3.-—Same more advanced. 
“ 4.—Same with mother-cell divided into two guard cells. 
“ 5.—More developed stage of same, 
“ 6,—Mature stoma. 
“ 7.—Cross-section of a young stoma. 
“ 8.—Cross-section of a mature stoma. 
` THE OPENING oF THE FLOWERS OF DESMODIUM SESSILIFOLIUM.— 
This Desmodium, which grows abundantly in Central Iowa, pre- 
about 1.5 centimeters long and are arranged in pairs, racemosely 
upon a spreading terminal inflorescence. The keel is at first en- 
closed within the wings, which in turn enclose the stamens and 
