SUMMAEY OF CURRENT RESEARCHES 



RELATING TO 



ZOOLOGY AND BOTANY 



(principally invertebrata and cryptoga:\iia) 



MICEOSCOPY, Etc.* 



ZOOLOGY. 



VEBTEBRATA. 



a. Embryology.! 



Artificial Parthenogenesis. J -Yves Delage lias given a complete 

 record of the experiments which have been made by himself and others 

 on artificial parthenogenesis. He contrasts the two chief theories, his 

 own and that of Loeb. Bnt the matter is not yet ripe for formulation. 

 One view is based mainly on the fact that the egg does not begin to 

 segment until some time after its return to its natural medium. It is 

 supposed that the parthenogenetic agencies do not directly induce seg- 

 mentation, l)ut modify the intimate constitution of the egg in such a 

 way that it becomes auto-partheuogenetic. The other view, suggested 

 in 1886 by Tichorairoff, supposes that the egg responds directly to 

 appropriate excitations. These stimuli differ for different kinds of eggs 

 and for eggs of the same kind at different stages of ripeness. Perhaps 

 there is some common factor in all the various stimuli which are effective, 

 but what it is remains unknown. 



Parthenogenetic Segmentation in Eggs of Hybrid Ducks.§— A. 

 Chapellier has studied eggs laid by a hybrid duck, the result of crossing 

 the musk duck {Oairina moschafa) and a domestic drake {Anas boscfias). 

 An egg from the oviduct showed distinct lilastomeres, but no nuclei 

 could be detected. In a laid egg the blastomeres showed rapid dis- 

 organization. 



* 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, uor 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 as actually 

 pttblished, 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. 



+ Verb. VIII. Internat. Zool. Kongress zu Graz., 1910 (1912) pp. 100-62. 



§ C.R. Soc. Biol. Paris, Ixxii. (1912) pp. 1010-12 (3 figs.). 



