56 



SUMMARY OF CURRENT RESEARCHES 



RELATING TO 



ZOOLOGY AND BOTANY 



(principally invertebrata and cryptogamia), 



MICKOSCOPY, Etc.* 



ZOOLOGY. 



VERTEBRATA. 



a. Embryologry. f 



Effect of Radium Rays on Ova.t — Charles Packard finds that very 

 mild radiation by means of the ii;amma rays from 50 mg. of radium 

 bromide produces an acceleration in the rate of cell division in the ova 

 of sea-urchins {Arbacia punctulata) without any abnormalities. These 

 rays have no effect on the development of Nereis limhata, or of Drosophila, 

 the pomace-fly. Moderate stimulation l)y means of the beta rays, 

 obtained by separating them from the gamma rays in a strong magnetic 

 field, brings about a retardation of growth in Arbacia and Nereis, 

 followed by no abnormalities. More intense radiation, in which both 

 beta and gamma rays are used, results in a liquefying of the protoplasm 

 in the Nereis egg, and the development is abnormal. The eggs of 

 Arbaria show no protoplasmic changes, but the chromatin is injured. 

 There is no evidence of parthenogenetic development. Acceleration and 

 retardation may be caused by a change in the rate of enzyme action 

 brought about by the radium treatment. 



Development of Neuraxis of Cat.§ — H. von W. Schulte and 

 Frederick Tilney give an account of the development of the central 

 nervous system of the domestic cat to the stage of twenty-one somites. 

 They deal especially with the interpretation of the forebrain in ternis of 



* The Society are not intended to be denoted by the editorial " we," and they 

 do not hold themselves responsible for the views of the authors of the papers 

 noted, nor for any claim to novelty or otherwise made by them. The object of 

 this part of the Journal is to present a summary of the papers a& actually pub- 

 lished, and to describe and illustrate Instruments, Apparatus, etc., which are 

 either new or have not been previously described in this country. 



t This section includes not only papers relating to Embryology properly so- 

 called, but also those dealing with Evolution, Development, Reproduction, and 

 allied subjects. 



t Journ. Bxper. Zool., xix. (1915) pp. 323-53 (3 pis.). 



§ Ann. New York Acad. Sci., xxiv. (1915) pp. 319-46 (20 pis.). 



