Amphicarpea monoica, 21 
or a very pale purple; when mature, the color varies from 
rich pink purple to purplish-brown. The seed has a whitish 
coat, upon which irregular purple patches occur. 
The histological structure of these legumes and their seeds 
presents striking characteristics. These will now be discussed 
under the proper headings. 
LEGUMES OF AERIAL TYPE. 
The outer epidermal cells are irregularly isodiametric ; 
stomata are very numerous. The few hairs that occur are of 
two varieties—small bladder-like forms and long unicellular 
ones. A cross section shows that the layer of epidermal cells 
is quite shallow; the hypodermal layer consists of indurated 
tissue. Maceration, and also surface view, shows this layer 
to be made up of rods, varying in length from .2 to .5 of a 
millimetre. They are pointed at each extremity and fit 
closely together. In the cross section from eight to ten rows 
of parenchymatous cells are next seen; occurring at irregular 
intervals are the vascular areas, accompanied by tannin canals. 
The inner epidermis has become quite indurated; in surface 
view the cells appear to have fused into long, narrow cells 
resembling fibres; these structures run longitudinally in the 
legume. The mesophyll is richly supplied with chloroplasts. 
The vascular areas, which constitute the dorsal and ventral 
sutures, show long delicate fibres, not easily separable, even 
after prolonged maceration. From examination of alcoholic 
and dry material at hand, dehiscence seems to be the result of 
increased induration of the inner epidermis and some cells of 
parenchyma adjacent to it. 
SEEDS OF AERIAL TYPE. 
Sections of the seed-coat show that the epidermal layer, 
which consists of indurated cells, occupies about one-third of 
the entire thickness of the coat. These cells contain the 
purple coloring matter—anthocyanin—apparently quite evenly 
distributed, and merge into a narrow, homogeneous, colorless 
