1920] WILSON— CROWN-GALL 61 



(figs. 42 , 43, 45). The central clear portion surrounded by periph- 



chromatin 



many 



The 



asm of the plasmodium 



lightly. It has not yet been possible to keep the plants infected 

 in the greenhouse long enough to secure the development of the 

 resting spores within the galls. 



In order to examine the plasmodia in older galls, sections were 

 stained with the triple stain and with haematoxylin. Only com- 

 paratively young galls were sectioned, as considerable foreign 



mycelium 



Infection 



by other fungi, and the consequent presence of a foreign mycelium 



organism 



to be expected because of the contact of the infected parts with 

 the soil. Sections of smooth intact galls showed no such signs 

 of foreign contamination. The same type of plasmodium, however, 

 that was found on the exterior of seedlings exposed to infection, 

 and within the tiny galls formed upon seedlings grown in infected 



containin 



resting spores. 



amoeboid 



were found in numbers (fig 47), preceding the formation of a Plas- 



modium 



streaming 



mass 



- 



tissue (fig. 45). In other cases it ramifies throi 

 network of naked protoplasm (fig. 42). Multiplication of the 

 Plasmodia may occur in these stages by budding and fragmenta- 

 tion (fig. 51). The walls of the host cells are < 

 gelatinized in advance of the main body of a 



ed 



ma tic 



The resting spores are formed in cavities or pockets occupied 

 by the parasite. Remains of host walls are mingled with the plas- 

 modial masses of the parasite, and a clear staining of the material 



: is almost unattainable. A yellow coloration pervades 



this stage h 

 i unstained 



of the spores. At the time of spore formation the yellow colora- 



limited 



