348 SUMMARY OF CURRENT RESEARCHES RELATING TO 



much in their mode of life ; many of them showing the character of 

 species unattached and influenced by currents. Others are bottom forms, 

 which are sometimes met with in plankton, such as Coscinodisca.* Ocnlus- 

 Iridis, C. gigas, Biddulphia membranacea, and Auricula insecta. Other 

 bottom species, such as Actinoptychvs Moelleri, are rare in this collection, 

 while others, such as Auricula insecta, Navicula dalmatica, and 

 Rhoicosigma compactum, are abundant. One of the most interesting 

 species is Gephyria media Arnott, a tropical Californian form, of which 

 three examples were present. The author is of opinion that the diatoms 

 of the original dredging have lived and multiplied during the six years 

 in the aquarium, where the conditions of light and temperature were 

 favourable. 



Fossil Diatoms.* — A. Forti gives a list of the species found by him 

 in samples taken from the Miocene deposits of Bergonzano (Reggio 

 d'Emilia). He intends to publish later a full account of the collection, 

 with diagnoses of new species. The present communication mentions 

 only the commoner and more easily recognised species. The most part 

 of the material consists of characteristic fragments of Coscinodiscus 

 gazellce Janisch, few of the specimens being entire. 



Rose-colour in Species of Myxophyceae.t — C. Sauvageau has made 

 some experiments on rose-coloured species of Myxophyceas, with a view 

 to studying their phycocyanin. Specimens of Lyngbya sordida Gom. 

 were obtained at a depth of about 6 to S metres, which were as red as 

 Erythrotrichia or Chantransia ; and these were treated with fresh-water, 

 or fresh -water mixed with ether, which caused the cells to increase 

 markedly in length and diminish in width. As a result of his experi- 

 ments, the author finds that marine species of Lyngbya, and probably 

 also of other Myxophycese which have a slender rigid sheath, treated 

 with fresh-water and ether, form excellent material for a spectroscopic 

 study of the dissolution of phycocyanin ; and the swollen cells, with a 

 non-permeable cell-wall, would be an interesting study from a cytological 

 point of view. The pigment of the rose-coloured Myxophyceae studied 

 replaces that which gives them their usual colour, and arises from its 

 transformation. 



In another note, the author remarks on the red Oscillarieae observed 

 in an aquarium of the laboratory at Banyuls-sur-mer, and he comes to 

 the conclusion that one of the influences, probably the principal one, 

 which causes their red colour is attenuation of light — in fact, they turn 

 red to save their lives, and the " complementary chromatic adaptation " 

 of Engelmann and Gaidukov has no part in it. They form dwarf 

 individuals, and in an aquarium they keep their red colour as if they 

 were a well characterised race, and prosper. The aquarium in question 

 had been untouched for five years, and the list of algse found flourish- 

 ing in it includes species of Chlorophycese, Phajophyceas, and Floridese. 



Pigment of Oscillatoria Cortiana.J — L. Bocat has made a study of 

 the spectrum of red plants of 0. Cortiana, comparing it with that of 



* Nuov. Notar.. xix. (1908) (Reprint). 



t C.R. Soc. Biol. Paris, lxiv. (1908) pp. 95-9. 



\ Tom. cit., pp. 101-2. 



