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164 The Botanical Gazette. [May, 
hair, and must exert a peculiar and powerful influence in order 
to bring about this change in form. _ 
Form of the microsymbiont in natural environment. 
In the protoplasm of the root hair, which is a more suitable 
pabulum than the nutrient vetch agar, and also in pointol 
view of economy in nature, the organism does not grow indit 
ferently as to direction but extends straight away down the 
root hair in its effort to reach the cortical parenchyma of the 
root. Probably the macrosymbiont alsoexerts some influence 
on the direction and definiteness of the growth of the micro 
symbiont. 
In figures 5 and 6 the organism presents the form of# 
thread or non-septate hypha, in size from one fourth to ont 
third the diameter of the root hair. It describes a somewh#t ] 
appearance. Rarely the organism enters the root hair neater 
the proximal end as shown in figure 7. In such cases the et! 
of the root hair is not deformed. The ends of the root nae 
frequently become deformed and variously curved from ous 
causes, but when it is due to this organism its presente seg! 
quite easily be noted. a 
The contents of the infecting hypha are homoge a 
rt 
Sents the appearance shown in figure 8, a section of the 
ng the infecting hypha. 
. "sure 9, the cell walls being represented in soe ae 
raight transverse line. This does not occur at 
