SUMMAEY OF CURRENT RESEARCHES 



RELATING TO 



ZOOLOGY AND BOTANY 



(principally invertebrata and cryptogamia), 



MICBOSCOPY, Etc.* 



ZOOLOGY. 



VERTEBRATA. 

 a. Embx-yolog-y.t 



Artificial Parthenogenesis and Fertilization.}— Jacques Loeb has 

 given a connected account of his experiments on the substitution of 

 physico-chemical agencies for the mysterious complex " living sperma- 

 tozoon." He adheres to his previously stated theory that two factors 

 are involved in what the spermatozoon effects — there is a change in the 

 surface of the egg, and there is a corrective factor. 



The unfertilized egg-cell dies a natural death ; the act of fertiliza- 

 tion will prevent this. The role of the spermatozoon as a bearer^ of 

 hereditary qualities is to be distinguished from its developmental role. 

 The two effects probably depend upon different materials in the sperma- 

 tozoon . Development may occur if a spermatozoon enters a de-nucleated 

 ovum; therefore, fusion of nuclei is not essential. Boveri's view that 

 the unfertilized egg-cell lacks the centrosome, which is the organ of cell 

 division, is disproved by the fact that astrospheres are formed in unfer- 

 tilized ova treated with hypertonic solutions. The maturation of the ova 

 of Chsetopterus does not normally occur unless the spermatozoon enters ; 

 centrosomes and astrospheres are present in the maturation division. 

 But it may occur if some potassium be added to the sea-water. Hence 

 the effect of the spermatozoon in this case is not due to the introduction 

 of a centrosome into the egg. 



Unfertilized sea-urchin eggs will develop into larvas if exposed for a 



* 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 as 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 Artificial Parthenogenesis and Fertilization. University of Chicago, 1913, 

 pp. 1-312. 



