ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 491 



Influence of Nutritive Salts on the Colouring of Oscillariese.* 

 W. Magnus and B. Schindler describe their experiments on the in- 

 fluence of nutrition upon the coloration of Oscillariefe. The work of 

 other writers is discussed on the effect of light as affecting Lhe colour. 

 Brunnthaler alone suggests that_ GJaeothece may be influenced by food- 

 substances. This suggestion is "taken up by the present authors, who 

 chose Phormidium aidumnale Gom. and Oscillaforia formosa Bory as 

 the subjects for their investigation. The result of their work is as 

 follows. The gradual multiplication and the stronger gro\\th of the 

 filaments cause the nutritive substances to be devoured, till finally the 

 necessary salts are no longer present. If the cells do not continue to 

 grow and divide, the continued assimilation inside the cell would cause 

 the physiological balance of the filaments to be gravely disturbed by the 

 accumulation of carbohydrates. If, however, they continue to grow 

 while lacking proper nutrition, they must degenerate and die. The 

 ecology of the yellow coloration would lie herein : that the colouring 

 material which assists assimilation becomes less and less, and at last 

 quite disappears. A resting-stage sets in, since all absorption of nutrition 

 ceases. It is always possible that with a similar minimum of nutritive 

 substances the coloration of shaded cultures would also be delayed, be- 

 cause with largely decreased assimilation the disturbances of metabolism 

 caused by lack of nutritive substances would be less strongly marked. 

 The cliange of colour observed by the authors stands in marked contrast 

 to the chromatic adaptation observed by Gaidukov. While in that case 

 the usefulness to the plant lies in a change of colour which favours 

 assimilation, the experiments of the authors show that the change in 

 colour is designed to lower the degree of assimilation. The change of 

 colour is useful to the plant, because only in that way can great dis- 

 turbances of metabolism be avoided. 



Mucilaginous Glands in Certain Laminariacese.t— C. Sauvageau 

 writes on certain glands in species of Laminariaceas which do not 

 possess mucilaginous canals. These were described by Okamura for 

 Undaria Pe^e/'se/?w??«!, by Miyabe for U. pinnatifida, and by Yendo for 

 U. undarioides. Yendo calls them mucilaginous glands, and describes 

 their structure and contents. In the present paper they are now 

 recorded in monostromatic plantlets of Alaria esculenta grown under 

 culture. The glands were not present on all the plantlets, but most of 

 them showed the glands when they reached a length of 400-500 [x. 

 The glands are either isolated or in groups of two or three, of the same 

 size as the neighbouring cells or larger, because they have lost the 

 power of division. They are really reservoirs of fucosan. The ordinary 

 cells of the plant contain some chromatophores and numerous globules 

 of fucosan, less than 1 /* in size. The glands appear more refringent 

 and almost colourless, because besides the chromatophores and the 

 small fucosan globules, they are as it were stuffed with larger and very 

 refringent globules, measuring 2—4 yu. Formol contracts their contents 



* Ber. Deutsch. Bot. Gesell., xxx. (1912) pp. 314-20. See also Bot. Centralbl., 

 cxxxi. (1916) p. 566. 



t C.R.. Acad. Sci. Paris, clxii. (1916) pp. 921-4. 



