AmphicarpcBa 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 



