336 WALDRON— THE PEANUT 



2. The hypocotyl shows a tendency to enlarge and become tuber- 

 ous unless growth conditions are ideal. This is apparently due to 

 a deposition of sugar from the stored food of the cotyledon which 

 is unable to be cared for by the root as fast as it is supplied. 



3. The stem is quite normal. Its epidermis, however, has crystal 

 cells in groups of two to four. The pith breaks down causing the 

 stem to become more or less hollow. 



4. The leaf, with numerous stomata on both the upper and lower 

 surfaces, has also, in both epidermal layers, small cells with a single 

 contained crystal in each when young. Later these cells become 

 fused into an "epidermal vessel," containing two to thirty crystals 

 arranged in irregular rows or groups. 



5. The fruit stalks or gynophores have been shown to be geotropic 

 in reaction, and the epidermal cells of the carpellary tips are marked- 

 ly granular, suggesting a possible perceptive relation in this regard. 

 These organs are very weakly hydrotropic and do not react to light 

 or darkness. The epidermis of the epigeal portion has crystal cells 

 like those of the stem. The epidermis of the hypogeal part becomes 

 elongated in the cell walls to form absorptive hairs. The second 

 layer becomes cambioid forming a phellogen-like hypodermis, and 

 this, by cambioid activity, may divide into two or three layers. The 

 bundles are separate and highly lignified in the outer phloem and in 

 the xylem. This gives mechanical strength for soil penetration. 



6. The young fruit, as it begins to swell, bursts the epidermal and 

 subjacent layers of the ovary, throwing them off. The next or third 

 layer, now the pseudo-epidermis, forms irregular, more or less branch- 

 ing absorptive pseudo-hairs. These are different in nature from 

 any of the other hairs formed on the plant, and are indicative of the 

 irregular growth of the spongy mesophyll of leaves. Beneath this 

 layer are developed several zones of cells similar to, and continuous 

 with, the pseudo-periderm of the gynophore. This is a marked 

 peculiarity in leaf tissue formation. 



7. Attempts to produce peanuts in the air by various means 

 failed to give definite results. Two succeeded by allowing the 

 gynophore to grow into water; several when grown on sphagnum 

 and also pure sand. None succeeded where the ovary was exposed 

 to light. The results indicate that water is an important factor, 

 but that contact, or darkness, or both may also be necessary. Young 

 fruits, if previously in contact with soil, and then exposed to the air, 

 continued to develop to a certain extent and turned green. The 



