33 



SUMMARY OF CURRENT RESEARCHES 



RELATING TO 



ZOOLOGY AND BOTANY 



(principally invertebrata and cryptogamia), 



MICEOSCOPY, Etc.* 



ZOOLOGY. 



VERTEBRATA. 



o. Embryolog-y, Evolution, Heredity, Beproduction, 

 and Allied Subjects. 



Relation of Spermatozoa to Certain Electrolytes. — J. Gray 

 i^Proc. Roy. Soc, 1920, 91, 147-57). A suspension of the spermatozoa 

 of Echinus miliaris in sea-water behaves towards trivalent positive ions 

 in exactly the same way as a suspension of negatively charged particles 

 of such colloids as albumen or globulin. It is only in those solutions 

 which are capable of maintaining the normal negative charge that move- 

 ment of spermatozoa can take place. Trivalent ions flocculate sperm 

 suspensions by removing the negative charge. The action of the 

 hydrogen ions is very intense, and changes the surface charge from 

 negative to positive without any immediate flocculation. The experi- 

 mental evidence goes to show that the surface charge on the spermatozoa 

 is of fundamental importance to their activity, and that this charge 

 depends upon the nature of the solutions with which the spermatozoa 

 are in contact. Just as particles of different colloids (or membranes of 

 different composition) possess different charges when in contact with 

 the same solution, so the eggs and spermatozoa of different species may 

 have different surface charges when in sea- water of the same composi- 

 tion. If, therefore, the possibility of fertilization of the Qg^ depends 

 partly on the mutual relationship between the surface charge of the ^gg 

 and that of the spermatozoon, it is possible that many cases of artificial 

 hybridization may find a simple solution. It is proposed to investigate 

 the surface charges of the spermatozoa of different species, with a view 

 to determining whether the possession of a critical surface charge con- 

 trols the fertilizing power of the sperm for eggs of the same and of 

 different species. J. A. T. 



* 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. 



D 



