EDWIN BROUN FRED 



333 



chyma and epidermis and thus forms a swelling on the side of the root/ In general, 

 nodules consist of a mass of thin-walled parenchymatous cells, rich in protein, and 



Fig. I. — Young pea plant with nodules 



Fig. 2. — Soy bean plants with nodules 



usually almost filled with bacteria. These thin-walled swollen cells occupy the greater 

 part of the tissue of the nodule. A layer of cork and branches of a vascular system are 



' Brenchley, W. E., and Thornton, H. G.: ibid., 98, 373. 1925. 



