324 MEMOIRS OF THE NEW YORK BOTANICAL GARDEN 



case the germ tubes near the stomata curved towards and grew 

 directly into them. But he obtained a similar result with leaves 

 injected with pure water only. In experiments in which he used 

 perforated mica plates, he found that the germ tubes near the 

 perforation always "grew toward the opening if it communicated 

 with a layer of medium in which no spores had been placed.'' Al- 

 though he had no occasion to follow out this line of work experi- 

 mentally, he advanced the hypothesis that Rhizopus is ''markedly 

 negatively chemotactic to some secretion of its own mycelium, and this 

 negative chemotropism is much greater than any positive chemotropism 

 it may have for food substances or oxygen.'' 



Also, in Miyoshi's control experiments, in which he used per- 

 forated membranes, he claimed that when the layers of medium 

 were of the same nature on both sides of the membrane, the spores 

 being sown in one of the layers, no turning towards the other 

 layer resulted. On the other hand, Fulton, after using essentially 

 similar methods, announced as follows: ''All of the fungi tested 

 show a tendency to turn from a region in which hyphae of the same 

 kind are growing, toward one destitute of hyphae, or in which the 

 hyphae are less abundant. . . . This may be regarded as a negative 

 reaction to stimuli from chemical substances which owe their origin 

 in some way to the grotuing fungus." 



Miyoshi's conclusions have in general been accepted by recent 

 writers of textbooks on plant physiology. The late Professor 

 Barnes^ described Miyoshi's results, but also wrote significantly 

 as follows: "Very striking reactions to chemical compounds of 

 many sorts have been ascribed to the hyphae of fungi and to 

 pollen tubes. Chemotropism of the latter may be maintained 

 still as it has not been seriously impeached; but that of fungus 

 hyphae has been brought under suspicion by the latest researches, 

 and may be either established or disproved by further study." 



The present paper is a short review of work which was carried 

 on at the Laboratory of Plant Physiology and Pathology, Im- 

 perial College of Science and Technology, London, under the 

 direction of Professor V. H. Blackman, in the hope of deciding 

 between the views of Clark and Fulton on the one hand and those 

 of Miyoshi on the other. 



' Coulter, J. M., Barnes, C. R., (S: Cowles, II. L". A textbook of botany for colleges 

 and universities i: 473-474. 19 10. 



