480 SUMMARY OF CURRENT RESEARCHES RELATING TO 



«• Crustacea. 



Reactions of Isopods.* — AY. C. Alice finds that certain conditions 

 known to affect the rate of metabolism of animals regularly affect the 

 rheotactic reaction of Asellus communis Say. Low oxygen, chloretone, 

 potassium cyanide, lowered temperature, suddenly heightened tempera- 

 ture, increased carbon dioxide tension, and starvation, all of which 

 depress the rate of metabolism of animals, also lower the positive 

 rheotactic response of Isopods. High oxygen, caffein, and a gradual 

 increase in temperature have the opposite effect. Allee measured the 

 rate of metabolism by means of the survival time in potassium cyanide, 

 and found that high positiveness in the rheotactive reaction is the 

 expression of a relatively high rate of metabolism, and low positiveness 

 of a low metabolic rate. 



New Copepod from Hollows on Tree Trunks.f — D. J. Scourfield 



describes Moraria arboricola sp. n. from little reservoirs of water on trees 

 in Epping Forest. It has not been found elsewhere ; most, if not all, 

 of the members of the genus live in wet or damp mosses. The genus 

 Moraria is very closely allied to the well-known genus Canthocamptus, 

 and is sometimes included with it. The animals do not swim well ; 

 they have great powers of clinging ; they are capable of living for a 

 very long time in quite small quantities of water and with scarcely any 

 food. On one occasion specimens continued in evidence for four and a 

 half years in a small glass tube in which the collection had been brought 

 home. 



Annulata. 



Effect of Radium on Fertilization in Nereis.} — Charles Packard 

 finds that radiated spermatozoa of Nereis Umbata react in two ways to 

 the normal egg. They may normally stimulate it, and be drawn in, but 

 subsequently fail to develop ; or they may fail to stimulate the egg 

 sufficiently and so remain outside. In the first case, the sperm nucleus 

 and aster may fail to develop and to fuse with the egg nucleus. In the 

 second case, the egg nucleus develops without an aster. 



The radiated egg at the time of fertilization may or may not extrude 

 the cortical layer. In either case, the maturation phenomena are more 

 or less abnormal. The germ nuclei develop abnormally and mitosis 

 does not occur, though the protoplasm may divide. 



Radiation of the fertilized egg results either in a failure of the fully 

 developed germ nuclei to fuse, or in abnormal division of the cleavage 

 nucleus. Eggs radiated before and after fertilization show very marked 

 evidences of protoplasmic degeneration. In general, both protoplasm 

 and chromatin are affected. It is suggested that the radium radiations 

 act indirectly on the chromatin and protoplasm by activating autolytic 

 enzymes, which bring about a degeneration of the complex proteids, and 

 probably by affecting other protoplasmic substances in the same manner. 



* Jouru. Exper. Zool., xvi. (1914) pp. 397-412. 



t Journ. Quekett Micr. Club, xii. (1915) pp. 431-40 (2 pis.). 



% Journ. Exper. Zool., xvi. (1914) pp. 85-128 (3 pis.). 



