SUMMARY OF CUEIIENT EESEAECHES 



RELATING TO 



ZOOLOGY AND BOTANY 



(principally invertebrata and cryptogamia), 



MICROSCOPY, Etc.* 



ZOOLOGY. 



VERTEBRATA. 



a.^EmbryoIog'y, Evolution, Heredity, Reproduction, 

 and Allied Subjects. 



Effect of Hydrogen Ion Concentration and Oxygen Content of 

 the Water on Regeneration and Metabolism in Tadpoles. — Minna 

 E. Jewell {Journ. Exper. Zool, 1920, 30, 461-507, 24 figs.). The 

 optimum hydrogen ion concentration for regeneration of the tadpoles of 

 Rana clamata is neutrality or near neutrality. Unfavourable concen- 

 trations inhibit regeneration directly and indirectly. The direct effect 

 on the regenerating tissue is relatively independent of the size of the 

 tadpole ; the indirect effect is greater in smaller tadpoles. In water of 

 low oxygen content both the rate of regeneration and the total amount 

 regenerated are dependent upon the amount of oxygen present. Both 

 rate and amount decrease with decrease in temperature. Differentiation 

 in regenerating tissues, as indicated by the appearance of pigmenta- 

 tion, is not retarded by unfavourable conditions so much as growth or 

 elongation. It is suggested that unsuitable hydrogen ion concentra- 

 tions, insufficient oxygen, low temperatures, and toxic substances affect 

 development, regeneration, oxygen metabolism, and duration of life in 

 the same way and according to the same laws. J. A. T. 



When does the Reducing Division Occur ? — Emile Guyenot 

 {Gomptes Rendus Soc. Phys. Hist. Nai. Geneve, 1921, 38, 53-5, 1 fig.). 

 In opposition to the usual view that the first maturation division is the 

 reducing division, halving the number of chromosomes, and that the 

 second division is an equation division, it is maintained that the real 

 reduction is effected by the second maturation division. In naturally 

 parthenogenetic animals there is no chromatin reduction, and that is 

 due to the suppression of the seco?id maturation division. In Daphnids, 

 Ostracods, Aphides and Rotifers there is a first polar body formed, but 

 no reduction. In Gi/clops strenuus and Artemia salina there is an 



* The Society does not hold itself responsible for the views of the authors 

 of the papers abstracted. The object of this part of the Journal is to present 

 a summary of the papers as actually published, and to describe and illustrate 

 Instruments, Apparatus, etc., which are either new or have not been previously 

 described in this country. 



