1893.] 



Action of Light on Bacillus anthracis. 



37 



out. Other Uredinea? exhibit the same phenomena, as Bachmann and 

 Zopf (' Die Pilze,' p. 145) showed. 



In short, the whole series of red, orange, and yellow pigments of 

 fungus spores and flowers are at least calculated to act as screens 

 which cut off more or less of the blue end of the spectrum, and they 

 agree remarkably throughout in this particular. 



Hoffmann (' Pringsh. Jahrb.,' II, p. 321) observed that the spores 

 of JJredo destruens germinated as well in light as in dark, whereas 

 those of Agaricus campestris, in one case, germinated better in the 

 dark than in the light — both cultures side by side.* Light did not 

 interfere with the germination of Fusarium Jieterosporium (a red form 

 on Rye), Trichothecium roseum, Penicillium glaacum, JJredo destruens, 

 and U. segetum. Here, again, we have the red-yellow pigments pre- 

 dominating, and, I suggest, acting as screens. With regard to Peni- 

 cillium, it must by no means be concluded that the peculiar bluish- 

 green hue gives us any information as to the rays transmitted to the 

 interior of the conidium : the spores of Aspergillus appear yellowish 

 by transmitted light, though, like Penicillium, they are blue-green by 

 reflected light, when seen in large masses. 



Low (' Verhandl. d. Zool.-bot. Gesellsch. in Wien,' 1867) also finds 

 no effect of light on Penicillium and Mucor stolonifer : so far as Peni- 

 cillium is concerned, this confirms Hoffmann, and my own attempts 

 with it and with Aspergillus glaucus are in accordance. 



Wettstein (' Sitzungsb. d. Wiener Akacl.,' 1885, B. 41, p. 39) found 

 that light inhibits the germination of the very delicate conidia of 

 llhodomyces Kochii, a parasite in the human alimentary canal. 



As regards my own older experiences with germinating spores, I 

 have a vivid recollection of the great difficulties experienced in 1886 

 with the conidia of Phytophthora infestans, and although the meaning 

 of the facts observed was not then clear to me, reference to my paper 

 on this fungus in the ' Quart. Journ. Micr. Sc.,' vol. 27, N.S., 1887, 

 p. 422, proves that the idea of increased oxidation under the influence 

 of intense light had already suggested itself to me. 



During my investigations into the biology of the orange-yellow 

 Urecline, Hemileia vastatrix, the fungus of the Coffee-leaf disease, on 

 the other hand, the impression is equally clear that little or no 

 difficulty occurred with germinations of any of these orange-coloured 

 spores, even in the intense tropical light of Ceylon. 



Many similar, but less vivid, impressions of the connexion between 

 light and germination occur to me, but little can be said as to their 

 value now. 



L. Klein (' Bot. Zeit.,' 1885, No. 1, p. 6) found that, as Rindfleisch 

 (' Virchow's Arch. f. path. Anat.,' B. 54) had already observed, the 



* At the same time, there is possibly a slight confusion here, for De Bary states 

 (p. 352) that the germination of A. campestris has never been certainly observed. 



