ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 737 



certain authors respecting the absorption of atmospheric nitrogen by 

 certain specialised hairs. After repeating the experiments upon which 

 these opinions were based, the author concludes that there is no evidence 

 to show that albuminoids present in the hair derive their nitrogen from 

 the air. 



Irritability. 



Organs of Light-perception in Foliage-leaves.* — F. Seefried has 

 investigated sixty species of shade-plants with reference to the organs 

 of light-perception in the leaves. In all of them the writer has found 

 light-perception organs on the upper surface of the leaves. In eight 

 species the epidermal cells hud level outer walls and arched inner walls ; 

 in two the outer walls were arched and the inner walls level, while in 

 thirty-three both the outer and inner walls were arched. In special re- 

 lation, also, to these modifications of the epidermis-cells, are to be noticed 

 such points as conical papillae over the outer walls. In many cases the 

 cells in the neighbourhood of vascular bundles, or near the edge of the 

 leaf, show a greater optical activity than the remaining epidermal cells. 

 Sometimes the light-concentrating cells are so powerful that they remain 

 active even when the leaf is slightly wet. Special means of light- 

 concentration are also provided by lens-like papillae, lens-like thickening 

 of the middle of the outer epidermal wall, etc. In some instances the 

 modification of hairs results in the formation of ocelli. Not unfrequently 

 the leaf cuticle has a granular covering, which prevents the injurious 

 effects of wet on the light-perception organs. 



Light-perception in Foliage-leaves. — Gr. Haberlandt contributes 

 a further paper dealing with light-perception. The author has observed 

 twenty-eight species, including species of Fagus, Betula, Ulmus, Quercus, 

 Malva, Ranunculus, Convolvulus, etc., and finds that his theory of light- 

 perception is still further confirmed. All the species examined possessed 

 organs for light-perception similar to those previously described. In 

 twenty-two the outer walls of the epidermal cells are more or less arched, 

 and the cells function as concentrating lenses. In the remaining six 

 species the outer walls are level, but the inner walls are plainly arched, 

 and the cells function in a similar manner to those of the preceding 

 species. The author considers that those who oppose his theory have up 

 to the present failed to disprove it. 



General. 



Floral Coloration in Relation to Bees4 — J- H. Lovell has made 

 observations upon Pyrus communis, Borago officinalis, and Gucurbita 

 maxima, in order to test whether conspicuousness of colour is an ad- 

 vantage to flowers. While these and other experiments, made wdth 

 honey placed upon coloured glass, seem to show that some allowance 

 must be made for the intelligence of the bees and other highly-developed 

 insects in discovering nectar, the evidence is conclusively in favour of 



* SB. k. Akad. Wiss. Wien, cxvi. (1907) pp. 1311-57 (4 pis.). 

 f Op. cit., cxvii. (1908) pp. 621-35 (1 pi:). 

 % Amer. Nat., xliii. (1909) pp. 338-49. 



