42 



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



Agaricus peziza, Gomphidius cut out most or all of the "blue and green 

 entirely, and in some cases, in fact — e.g., Peziza sanguinea — only allow 

 red and a little orange to pass at all. 



Now comes a curious point with regard to the violet pigments of 

 Cortinarius, Agaricas, and Lactarius. According to Bachmann, they 

 cut out all the red below the line B, and all the indigo-violet beyond 

 the line Gr, together with more or less of the blue-green. Stranger 

 still, the violet pigment of Lactarius deliciosus cuts out everything 

 beyond the line D except a little blue between F and Gr, and trans- 

 mits most of the red-orange and yellow. 



Bachmann himself points out that two colouring matters, a yellow 

 and a violet, occur side by side, and he also refers to the transient 

 nature of some of these violet colours, which turn yellow with age. 



Since such cases may be common, we must not accept a violet pig- 

 ment without close examination, for it may be due to a mixture, or to 

 superposition, or to other causes, and is by no means necessarily a 

 colour screen in the sense that the orange and red pigments of others 

 are. 



The orange-yellow pigments of the spores of several Uredineae show 

 spectra very uniform in type. The indigo-violet from Gr onwards all goes 

 out, and strong absorption bands are formed in the blue between F and 

 Gr, and again at the line F. Most of the red, orange, and green are 

 transmitted. Bachmann shows that the oily masses in these spores of 

 Uredineas are true fats, and the orange colouring pigments are 

 associated with them. In connexion with the easy germination of 

 such spores, it is interesting to note that these orange-coloured fatty 

 drops pass into the germinal hyphas. 



As regards the colours in Phy corny cetes, we know almost nothing of 

 use in the present connexion. The spores and sporophores are often 

 coloured with yellow or orange pigment, e.g., Pilobolus, Mucor, Chytri- 

 diacece, but, although Zopf says (' Die Pilze,' p. 148) these colours are 

 also associated with fats, they still require spectroscopic investigation. 



Pollen. 



Another very interesting case is that of pollen, the microspores of 

 the flowering plants. It is obvious that the pollen grains are often 

 exposed for many hours to intense insolation in the concave cup of 

 the corollas of many flowers and on the bodies of bees and other 

 sun-loving insects. Now a pollen grain is just such a storehouse of 

 fatty oils as, according to my view, ought to be protected from the 

 destructive rays, and in the vast majority of cases the deep orange 

 colours of these spores accord well with the purpose suspected. 



Even in the very few references to the colours of pollen that I can 

 find, however, there are cases which at first sight seemed to present 

 great difficulties. 



