ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 785 



describes his method for obtaining pure solutions of the pigments, and 

 then discusses their various physical and chemical characters. The two 

 bodies are of a proteid nature, and Kylin suggests the name phyco- 

 chromoproteids for them. Both are insoluble in pure water, but dissolve 

 after the addition of a minute quantity of alkali or neutral salt ; by 

 boiling or by the addition of an adequate proportion of acid or alkali 

 the albuminoid components are separated off from the coloured com- 

 ponents. 



Effect of Light on Algae.* — P. A. Dangeard gives the results of 

 his investigations of phototactism, assimilation, and phenomena of 

 growth, by means of special apparatus. As to phototactism, he distin- 

 guishes two quite different types : — (1) that of the EugleneaB, which 

 seek the most refrangible rays of right ; (2) that of the Oscillariaa, 

 which range themselves under the less refrangible rays. He finds that 

 it is only under the action of certain rays determined by the coloured 

 screens that the oxygen bubbles are formed on the filaments of algae ; 

 under other rays Mesocarpus, for instance, turns black. As to growth, 

 he states that in the case of Ghlorella vulgaris it is the chlorophyll 

 absorption-band situated at B and C which is effective in growth as well 

 as in assimilation. Finally, he says that the spectrogram of a culture of 

 a sulphur-bacterium, probably Thiocystis violacea, shows the same cha- 

 racters of development as does Ghlorella, and behaves like a green alga. 



Nuclear Autochromatism in Algae.j — P. A. Dangeard publishes a 

 note on an instance of nuclear autochromatism in a Desmidean genus 

 Penium. In some cultures injured by excessive solar energy certain 

 cells had been killed, and had the appearance of having been subjected 

 to a fixing reagent, showing all the details of their nuclear structure. 

 After death the pigment had played the role of a staining reagent. 

 The researches are to be pursued further, in order to determine whether 

 other algae can stain their protoplasm. 



Algal Figures on Culture Flasks. f — M. Molliard gives an ex- 

 planation of the vertical lines designed by various aquatic algas on the 

 sides of glass culture-flasks standing near windows. Dangeard had 

 experimented with Ghlorella, and explained the vertical strias of the 

 plant deposit as being due to local intensity of light. Molliard admits 

 this factor, but shows that gravity also intervenes as an explanation of 

 the solely vertical vegetation of the algae. Dangeard, in reply, finds it 

 natural enough that gravitation should have some influence in the 

 matter ; but, as luminous intensity and the nature of the radiations 

 play a very active part, he holds that each of the three factors should be 

 studied in each particular case. 



Anatomy of Polyides and Furcellaria.§ — G. Denys gives an account 

 of his investigations of the anatomy of Polyides rotundas and Furcellaria 

 fastigiata, two algas which, in the absence of reproductive organs and 



* Bull. Soc. Bot. France, lvii. (1910) 17, pp. 315-19. 



t Bull. Soc. Bot. France, lvii. (1910) pp. 453-5. 



: Bull. Soc. Bot. France, lvii. (1910) p. 519. 



§ Beih. Jahrb. Hamburg Wiss. Anstalt, xxvii. (1910) pp. 1-31 (figs.) 



