36 Prof. Marshall Ward. Experiments on the [Feb. 16, 



The assumption that the action is direct on some oxidisable body, 

 like a fat, in the spore would help us to explain a good many facts, 

 and among others the death of the protoplasm, if insolation is com- 

 plete, because we know how intolerant of traces of acids Bacillus 

 anthracis is, and inhibition and attenuation if the insolation is incom- 

 plete, and the protoplasm not so far injured that it cannot work up 

 the remnants of reserve materials left. 



That this point is one well worth further investigation is too ob- 

 vious to dwell upon here, and I hope to succeed yet in discovering 

 what is the body destroyed. 



Literature. 



There are, so far as I can discover, very few statements to hand as 

 to the influence of light on spores other than bacteria,* and their 

 germination ; and, indeed, as shown by Elfving's excellent summary 

 of the literature in his 1 Studien iiber die Einwirkung des Lichtes 

 auf die Pilze,' as to the influence of light on Fungi in general. It has 

 been the custom to regard the effects of light on the Fungi as not 

 essentially different from those on other plants ; in accordance with 

 De Bary's general statement to that end on pp. 352 — 353 of his 

 ; Comp. Morphol. and Biol.,' Engl. Ed., 1887. 



Zopf ('Die Pilze,' 1890, p. 199) believes that light, as a rule, 

 exerts no influence whatever, either on the germination of the spores 

 or on the development of the mycelium, though he himself quotes De 

 Bary's and Wettstein's statements to the contrary, and I have myself 

 observed similar cases. 



De Bary (' Ann. des Sc. Nat.,' vol. 20, 1863, p. 40) found that the 

 zoospores of certain Peronosporeas are inhibited by light in their 

 germination, e.g., P. macrocarpa and Phytophthora infestans, a fact I 

 should correlate with their delicate walls and want of protective 

 colour screen. On the other hand, De Bary (' Ann. des Sc. Nat.,' 

 IV Series, vol. 20, 1863, p. 54) showed experimentally that the 

 pustules of Uromyces appendiculatus appear preferably on that side of 

 the leaf which receives most light, and this is indicated by their 

 occurrence on the upper faces of these organs, facts quite in accord- 

 ance with the deep orange-red colour of this fungus. 



In Uromyces and others of these orange Uredineae, the colouring 

 matter is associated with fatty drops (Bachmann, " Spectroskop. 

 Unters. von Pilz-farbstoffen," in ' Progr. des Gymnas. zu Plauen,' 

 Ostern, 1886, pp. 9, 21), and shows two absorption bands, one on the 

 boundary between the green and the blue near F, the other in the 

 blue between F and G, and the whole of the violet beyond G is cut 



* The literature, so far as bacteria are concerned, will be found in ' Boy. Soc. 

 Pjoc.,' vol. 51, 1892 p. 237, and vol. 52, 1893, p. 393. 



