ZOOLOGY AND BOTANY, MICROSCOPY, ETC 385 



tube-like canals. Altogether it is, he says, quite evident that this 

 hyaline protoplasm, and not any hypothetical "gallerte," flows hack and 

 forth in these keels, and operating upon the surroundings through the 

 minute clefts propels the diatom, rolls it over, and stands it upon its end. 

 This is a kind of apparatus for diatom locomotion easily understood ; 

 and besides being in comfortable agreement with the nature and pecu- 

 liarities of the phenomena to be explained, it has the not inconsiderable 

 advantage of being demonstrable. 



Behaviour of Chlorella in White and Coloured Lights.* - - P. A. 

 Dangeard publishes a note on the photographic properties of Chlorella 

 vulgaris. A culture of this alga, in a cylindrical glass jar containing 

 Knop's liquid, developed itself on the sides of the jar in flue parallel 

 lines, recalling Frauenhofer's lines in the spectrum. Upon investigation 

 it appeared that these lines corresponded with the shadows of the 

 window-bars of the laboratory focused on the sides of the jar. The 

 Chlorella preferred a situation not strongly illuminated. This sensi- 

 tiveness of Chlorella may serve usefully in laboratory experiments. 



In a subsequent paper f Dangeard describes further experiments, 

 and shows that it is not the case that Chlorella moves into the position 

 best suited for it, but that being distributed equally over all the wall- 

 surface of the jar it develops most abundantly at those spots where 

 the illumination is best suited to it. By the use of monochromatic 

 screens and of three-coloured screens as used in photography, he found 

 Chlorella to develop best in red and orange light, feebly in violet, and 

 not at all in green. If a quick result is required, the number of oxygen 

 bubbles evolved in the different zones of coloured light in a given time 

 may be compared. One interesting experiment was the placing of a 

 Chlorella culture behind three three-colour screens and a large screen of 

 thick black paper ; strangely enough, in bright sunshine the evolution of 

 oxygen-bubbles took place almost as freely under the black screen as 

 under the three-colour screens. Some non-luminous rays presumably 

 passed through the black screen. 



Study of Diatoms in Sedimentary Deposits.} — A. Lauby, in de- 

 scribing a new technical method for a paleophytologic study of ancient 

 sedimentary deposits, has plenty to say about the Diatomaceae and the 

 important evidence which they yield. They have, however, in the past 

 led careless workers into error. The employment of impure water in 

 washing the material has made some modern diatoms appear to have 

 been in existence in the Coal-period. Again, a modern deposit may have 

 been derived by denudation from an older deposit, and the same diatoms 

 naturally appear in both. The author gives practical instructions as to 

 how the study should be pursued, what methods adopted, what precau- 

 tions observed. 



Classification of Alg£e.§ — J. Gomere writes a short essay on the 

 classification of algae. He begins by a resume of the various treatments, 



* Bull. Soc. Bot. de France, lvi. (1909) pp. 368-70 (1 pi.). 



t Tom. cit., 503-8. 



X Bull. Soc. Bot. France, lvi. Mem. 15 (1910) 110 pp. 



§ Mem. Acad. Sci. Toulouse, ser. 10, ix. (1909) pp. 219-26. 



