138 FUNGOUS DISEASES OF PLANTS 



rest and penetrates the epidermal cell of the host there is con- 

 siderable growth in this single cell of the fungous, vegetative 

 body ; (2) multiplication of the nuclei in the vegetative body until 

 a considerable number is formed ; (3) progressive cleavage in the 

 multinucleate body from the surface inward, such that uninu- 

 cleate bodies (termed protospores) are produced, accompanied 

 with marked shrinkage of the segments ; (4) growth, increase 

 in size of the protospores, followed by nuclear divisions ; (5) the 

 development of cell walls about the multinucleate spores, food 

 storage, and passage into a ripened or resting condition ; (6) 

 germination by the production of a sporangium from each multi- 

 nucleate spore, each sporangium producing a number usually 

 eight to twelve of the uninucleate, uniciliate spores ; (7) the 

 active motile stage. 



In a recent study Kusano reports that a Synchytrium on Pueraria, 

 and also Synchytrium decipiens, affect only nonchlorophyllous cells 

 of the mesophyll. In each he finds that the cell wall of the affected 

 cell (and in time of neighboring cells) is dissolved. Eventually con- 

 siderable lysigenic cavities are formed in which the fungous body 

 lies "encased by the symplast of the host" (Fig. 41). 



Synchytrium. In this genus the fruit body, upon reaching 

 maturity, forms no highly resistant cell wall about itself, but by 

 immediate differentiation of the protoplasmic contents becomes 

 the sporangial sorus. 



Pycnochytrium. The fruit body is a thick-walled resting spore, 

 which after a period of inactivity germinates by the protrusion of 

 its contents in the form of a thin-walled sporangial sorus. The 

 sporangia produce uniciliate swarm spores. 



III. CRANBERRY GALL 

 Synchytrium Vacdnii Thomas 



HALSTED, B. D. Some Fungous Diseases of the Cranberry. N. J. Exp. 



Sta. Built. 64: 1-40. figs. 1-18. 1889. 

 SHEAR, C. L. Cranberry Diseases. Bureau Plant Industry, U. S. Dept. Agl. 



Built. 110: 1-64. pis. 7-7. 1907. 



It attacks young stems and leaves as well as flowers and fruit. 

 The small galls, reddish in color, are produced on the surfaces of 

 the parts affected in great numbers. The fungous body consists 



