i9 2 °l WILSON— CROWN -G A LL 59 



Fusion stages may be quite clearly followed in material fixed 

 and stained on the slide. Fig. 28 shows two zoospores, a large 

 one and a small one, apparently in the same condition as when 



from 



The nuclei of stained zoo- 



spores often appear to be within a vacuole because of their position 

 w r hen fixed to the slide. The larger zoospore, either before or at 

 the approach of the smaller one, may put out one or more pro- 

 jections in the direction of the latter (fig. 33). Fusion may take 

 place at the apex of such a projection (figs. 34, 36). The two 

 nuclei may be seen within the larger body following the fusion 

 (fig. 35). The fusion of the nuclei has not been observed. Figs. 

 37 and 38 possibly indicate stages following a fusion succeeded by 

 a division of the fusion nucleus. Many small nuclei appear in 

 the body of the organism at this stage (fig. 37), and there is some 

 evidence of a cell multiplication by budding (figs. 38, 44, 51). It 

 is entirely possible, however, that a multiplication of the nuclei 



to 



may 



any nuclear fusion. The observations at this point do not justify 



staining 



makes the following 



cult. There seem, however, to be some grounds for maintaining 

 that the phenomena just described constitute a true case of heter- 



ogamy. 



movements 



and a nucleus of average proportional size. On the other hand, 



smaller cells are swift of mo\ 



in 



The oil drop probably serves as reserve 



temporary 



does not occur, or of the zygote in case it does occur. 



In order to secure the development of the zoospores upon the 

 host, young alfalfa seedlings were carefully washed and introduced 



small vessels containing sterile distilled 



the 



roots and the lower parts of the stem were immersed. A gall 

 from an infected plant was carefully washed, crushed, and intro- 

 duced into the water. After one day the seedlings were removed 

 from the water, crushed under cover slips on slides, and examined 

 for evidence of the presence of the parasite. On and In the tissues 

 of the host which had been at the water level were numerou 



