314 SUMMARY OF CURRENT RESEARCHES RELATING TO 



tions of the organisms (except Protozoa) are considered in most careful 

 detail. Finally, a zoogeographical section is devoted to a brief con- 

 sideration of the distribution of the species, the occurrence of local 

 variation, and the zoological grouping of the lakes. The paper is 

 described as introductory to a more biological treatment of the subject, 

 and though from its nature it does not lend itself to the purposes of an 

 abstract, is of great importance to the student of fresh-water plankton. 

 The careful systematic treatment of such a difficult group as the Clado- 

 cera, for example, should be specially mentioned as likely to prove of 

 enormous value to future investigators, while the extraordinarily careful 

 treatment of variation should make the paper a mine of wealth to students 

 of evolution. 



River Plankton.* — Herr S. Prowazek studied the potamo-planktun 

 of the Moldau and Wotawa (S. Bohemia), during August, September, and 

 part of October 1898, and gives lists of the organisms found. Both 

 streams showed great poverty of organic life, especially as regards the 

 Metazoa. There were no Crustacea and very few Rotifers, and among 

 the Protists truly pelagic forms were found to be rare. Many charac- 

 teristic forms disappeared in October when the water rose. 



Organic Evolution and Altruism.f— Mr. W. H. Wynn has an in- 

 teresting essay on this subject. Following, for instance, the authors of 

 ' The Evolution of Sex ' (a work which seems to have been utilised not 

 a little though never referred to), he points out the neglect of the 

 altruistic factor in considering the problem of organic evolution. 



What is Life ? $ — Prof. F. J. Allen argues for the following views. 

 Every vital phenomenon is due to a change in a nitrogenous compound, 

 and, indeed, in the nitrogen atoms of that compound. There is no 

 vital action without transfer of oxygen, and the transfer is performed 

 by nitrogen (often assisted by iron). In the anabolic action of light on 

 plants, the nitrogen compounds are affected primarily, and the C0 2 and 

 water secondarily. In the living and active molecule the nitrogen is 

 situated centrally, and is often in the pentad state. In the dead molecule 

 it is usually peripheral and in the triad state. The oxygen store of the 

 living molecule is more or less united with the nitrogen, but passes to 

 some other element at death. The nitrogen of the living molecule is 

 combined in a complex and perhaps changeable manner, the compound 

 resembling in some respects the cyanogen compounds, in other respects 

 the explosives such as nitro-glycerin. Life in its physical aspect is the 

 culmination of that chemical instability in certain elements which has 

 always kept them circulating at the earth's surface. 



Tunicata. 



Pacific Tunicata.§ — Dr. C. Ph. Sluiter describes the Tunicates of 

 Schauinsland's Pacific Expedition. As is usually the case with Tunicates 

 from little-known regions, the collection includes a large number (25 out 

 of a total of 36 species) of new species ; but it is to be noticed that in 

 many cases, notably in the genera Leptcclinum, Amaroucium, and Poly- 



* Verb. Zool.-bot. Ges. Wien, xlix. (1899) pp. 446-50 (1 fig.). 



t Proc. Birmingham Nat. Hist, and Phil. Soc, xi. (1898-99) pp. 1-43. 



t Tom. cit., pp. 44-67. 



§ Zool. Jahrb. ' Abt. Syst), xiii. (1900) pp. 1-35 (6 pis.). 



