1916] GRAVES—CHEMOTROPISM IN RHIZOPUS 369 
attraction resulting from positive chemotropism remains fairly 
constant. 
g. If the preceding conditions are true of fungi in general, it is 
probable that the distribution of a fungus in its host is influenced 
mainly, not by positive chemotropism, but by the dominant ney 
tive chemotropism due to its own staling products. 
10. The part played by osmotropism in these reactions must, 
if any, be a very small one. 
In conclusion, the writer desires to express his great indebted- 
ness to the invaluable suggestions and hearty cooperation of 
Professor V. H. BLACKMAN, at whose instance this work was under- 
taken. The main part of the investigation was carried on under 
Professor BLACKMAN’s direction at the laboratory of Plant Physi- 
ology and Pathology, Imperial College of Science and Technology, 
London, but the work was finished at the Osborn Botanical 
Laboratory of Yale University. 
Connecticut COLLEGE FOR WOMEN 
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