ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 349 



phycocyanin and phycoerythrin, and he finds that the spectra of these 

 two substances and that of the pigment of 0. Cortiana are related but 

 not identical. The normal pigment of that species has not been studied ; 

 but the author is of opinion that when the red colour is assumed by the 

 plant, it is no longer able to assimilate in orange radiations, but uses, 

 like Flor ideas, green radiations. He comes to this conclusion, while 

 granting that the action of the ether has helped to disperse the absorp- 

 tion band of the orange. Bands i., ii., and hi. of 0. Cortiana correspond 

 approximately to the third, fourth, and fifth bands of chlorophyll, where 

 assimilation is very feeble. 



Plankton of Mofjord.* — E. Jorgensen gives some interesting results 

 of his investigations of the natural conditions of Mofjord, which is the 

 innermost part of a long narrow fjord in the neighbourhood of Bergen. 

 The water reaches a depth of 217 in., and is rather fresh on the surface, 

 varying however from 1-20 mille in salinity, according to the quantity 

 received from streams. The greatest thickness of this sheet of fresh- 

 water is about 10-12 m. Statistics of the salinity and distribution of 

 gases below this sheet are given. The plankton in the upper layers 

 (0-35 m.) is very rich, while below that only empty frustules occur as a 

 rule. The dominant species are : GJmtoceras curvisetum, Sceletonema 

 costatum, and Ceratium spp. A few fresh-water forms, Melosira varians, 

 Surirella ovata, and Tabellaria flocculosa, have been noted, more or less 

 scattered. 



Indian Ocean Phytoplankton.! — CI. Karsten publishes the last part 

 of his account of the phytoplankton collected on the ' Valdivia ' Expe- 

 dition in 1898-9, and the whole work is a valuable and important con- 

 tribution to the study of those organisms. In the present contribution 

 he gives (1) lists of the species which were found in the different hauls 

 in the Indian Oeean ; (2) a systematic part, and (3) a general part. In 

 the systematic part all the species found in the Indian Ocean are de- 

 scribed ' and figured, except such as had been treated in previous con- 

 tributions. Among the diatoms one genus, 35 species, and 6 varieties 

 are new, and of Peridineae 15 species and 6 varieties. In the general 

 part all questions relating to the investigation of plankton are dis- 

 cussed in the light of the new results obtained by the ' Valdivia ' Ex- 

 pedition. The author regards the Indian Ocean as a more or less 

 compact floral unity, and the differences which he observed he considers 

 as the result of a greater or less intermixing of neritic forms. The 

 vertical distribution of the phytoplankton is not markedly different from 

 that of the Antarctic region. The greater number of the algai occur 

 above a depth of 200 in., generally between 60-100 in., while below 

 400 m. only isolated living cells are found. On the surface live the 

 Schizophyceas and the long-horned light Geratia ; then follow C/mtoceras 

 peruvianum and chains of the lighter species of Rhizosolenia, then the 

 more compact Geratia amphisolenia, the large-celled RhizosoUnia, and the 

 remaining species of G/mtoceras. This is the vertical order down to 



* Trondjem kgl. norske Vidensk. Selskskrift, 1906, No. 9 (1907) 40 pp. 

 t Wiss. Ergeb. Deutsch. Tiefsee Exped. ' Valdivia.' 1898-99, ii. 2 (Jena. 1907) 

 pp. 223-548 (20 pis.). See also Bot. Zeit., lxvi. (1908) pp. 87-101. ? 



