PLATE 45 
1. —Inner three-quarters of one of the middle proliferations on Plate 5, showing its 
origin from the inner face of the vascular bundles (VB) with tracheae and sieve tubes 
of its own at Tr. At MB are two concentric medullary bundles. X70. 
2. —Ricinus stem treated with strong ammonia (PI. 5) showing four whorls of vascu¬ 
lar tissue (concentric medullary bundles) similar to those occurring in crowngalls: 
i. e., the central tissue is phloem and the outermost cylinder is xylem. The pith 
cavity is in the direction of the arrow. Below is a branch gap (?). X160. Compare 
with Plates 40, 43, and 65. 
67908°—17 -8 
