VOLUME XLI NUMBER 2 
BOTANICAL GAZETTE 
FEBRUARY, 1906 
CHEMOTROPISM OF FUNGI! 
HARRY R. FULTON. 
HISTORICAL. 
De Bary (5) advanced the supposition that the oogonia of 
certain Phycomycetes not only attract the antheridia-producing 
branches, but determine the formation of these branches as well. 
The same writer (6) later raises the question as to whether the bend- 
ing of a germ-tube toward the epidermis of its proper host, but not 
toward every membrane or moist surface, may not be brought about 
by a specific reaction in the parasite, induced by physical or chemical 
stimuli which may be supposed to operate through unknown secre- 
tions from the host plant. This was written, though not published, 
before PrEFFERr’s first studies (25) on the reactions of motile unicel- 
lular organisms to chemical stimuli. During the progress of his 
studies with Saprolegnia swarm-spores, he observed that the hyphae 
of the fungus turned toward the nutrient substances, and he supposed 
that chemical agents might in many cases determine, the direction of 
growth of these and other hyphae. 
KIHILMAN (16) observed that if a germinating ascospore of Mel- 
anospora parasitica lies at a distance of not more than four or five 
spore-diameters from a growing hypha of its host, Jsaria farinosa, 
the direction of growth of the latter is deflected toward the spore of 
‘the parasite until there is contact with its germ-tube. 
According to BREFELD (1), the fact that neighboring sporidia of 
Ustilaginaceae conjugate in pairs, the connecting tubes taking the 
shortest course between two sporidia, may be explained by a 
a directive chemical influence. 
* Contribution No. 4 from the Botanical Laboratory of the University of Missouri. 
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