IN. CLEOME AND IsOMERIS. 247 
It may be noted in passing that stomata are also present in 
the inner ovarian wall in relatively large numbers. 
The occurrence of stomata in ovules has been recorded by 
various authors—by Schleiden* in Canna, by Czech f in 
Tulipa Gesneriana, and by Guérin { in Dipterocarpus, among 
others, but the physiological significance of their location in the 
ovule is not referred to. 
If the outer integument be removed from living material and 
appropriately stained, the presence of conspicuous starch-grains 
in the guard-cells of the stomata, and in the cells of the underlying 
layer, can be clearly demonstrated. This fact is suggestive of the 
possibility of photosynthetic processes being carried out in the 
Fic. 4.—Stoma from the outer integument of ie ovule of Isomeris 
arborea, in surface view. Xabout 500. 
ovule, though the quality of the light which filters through the 
ovarian wall must be appreciably diminished. 
In the seed the outer integument becomes tubercled, the 
stomata then being found mainly on the multicellular excres- 
cences. Starch-grains were again discernible in the guard-cells 
and in the cells of the hypodermal layer of immature seeds. 
Isomeris arborea, Nutt. 
The outer integument of the ovule of Isomeris is double- 
layered, as in that of Cleome, but the inner integument is many- 
layered, the aqueous tissue being two to three cells broad, while 
on its inner side there are four or five layers of smaller cells. 
The fibrous layers have their origin in the same region as in 
* M. J. Schleiden, Beitr. zur Botan. ogee Pa 10, 
; ai Czech in Bot. Zeitg., xxiii (1865), p 
P. Guérin in Bull. Soc. Bot. Fr., lviii pity .. 22, 
