WAI.DRON— THE PEANUT 315 



raised nor sunken. They average from fifteen to twenty per square 

 millimeter, and each is surrounded by two unequal subsidiary cells. 

 Both epidermal layers are also supplied with numerous specially 

 formed crystal cells (Plate LXXIX, Fig. 5.) which, when the leaf is 

 young, are small, each containing a single rounded crystal. Later, 

 these cells become fused into what might be called an "epidermal 

 vessel," irregular in shape and containing two to thirty crystals 

 arranged in clusters or irregular rows. Solereder^^ notes the pres- 

 ence of these, but does not mention the later fusion into one. In 

 attempting to determine the origin of these, a stem apex with a 

 young bud attached was sectioned. It was found that in very 

 young leaves all the epidermal cells were alike, and devoid of crystals. 

 Immediately after the last cell division, however, some of the cells 

 increased in size to form the normal epidermis, while others remained 

 small to become the crystal-containing cells. In some of these it 

 was noted that the small crystal seemed to be a part of the nucleus, 

 possibly formed within and by it. It was in a pellicle-like projection 

 which later separated away. In all such young cells the crystal was 

 imbedded in a protoplasmic matrix which gradually became mucil- 

 aginized in old cells. The mesophyll of the leaf is composed of a 

 two- to five-layered palisade tissue immediately below the upper 

 epidermis and a single layer of water storage cells next to the lower. 

 These two features are more typical of a xerophytic plant than is 

 the presence of the above mentioned stomata. A loose, comparative- 

 ly thin layer of spongy mesophyll separates the palisade and water 

 storage layers. The petiole and lower epidermis of the leaflets bear 

 the typical three celled hairs already mentioned as found on the stem. 



Fruit 



The anatomy and physiology of the fruit were carefully studied 

 for the purpose of discovering, if possible, some facts concerning its 

 hypogeal development. Among other members of the Leguminosae 

 to share this peculiarity are Amphicarpa monoica, Trijolium subter- 

 raneum^ species of Voandzeia and of the new African genus Ker- 

 stingiella. Amphicarpa bears two kinds of flowers, and accordingly 

 two forms of fruit, only one of which develops underground. The 

 flower which gives rise to this subterrenean fruit is formed and al- 

 ways remains underground. Trijolium subterraneum bears but one 

 type of flower formed in heads. The peduncle, after flowering. 



