PLATE 44 
1. —Cross section of stem of Ricinus communis treated with ammonia (PI. 5) showing 
the development of an abnormal (?) medullary bundle (MB) and its relation to the 
normal bundles. Pith above, inner part of woody ring below. X160. 
2. —Cross section of Ricinus stem treated with strong ammonia (Pl. 5) showing inner 
part of xylem, many tracheae of which are filled with thyloses ( Th ) as in vascular 
bacterial diseases. At the right there is a little of the proliferated tissue, including 
one of the curious medullary bundles (MB) the center of which is phloem. Same 
magnification. 
