SUMMARY OF CURRENT RESEARCHES 



RELATING TO 



ZOOLOGY AND BOTANY 



(PKINCIPALLY INVEETEBRATA AND CRYPTOGAMIA), 



MICROSCOPY, Etc.* 



ZOOLOGY. 



VERTEBRATA. 

 a. Embryology. t 



Electrical Conductivity of Ova.J — J. Gray has tested the electrical 

 conductivity of fertilized and unfertilized ova of starfish and sea-urchin. 

 He finds that the entrance of the sperm into the egg causes an increase 

 in the electrical conductivity of the egg. This condition usually attains 

 its maximum within ten minutes of adding sperm to ripe eggs. The 

 increase in conductivity is followed by a process which returns the con- 

 ductivity of the fertilized egg to or towards that of the unfertilized egg. 



The changes may be purely physical or purely chemical, or both. 

 The egg in the unfertilized state is remarkably impermeable to electro- 

 lytes, and can almost certainly be regarded as being enclosed within 

 a semi-permeable membrane. In its unstimulated condition this 

 surface must necessarily be polarized. If now this polarization be 

 destroyed, the membrane must become more permeable to ions than 

 before. On this view the entrance of the sperm effects the depolariza- 

 tion of the plasma-membrane. After about fifteen minutes this mem- 

 brane must become polarized again, but the mechanism whereby this 

 is effected is not at present clear. On the other hand, if the sperm 

 carries an enzyme into the egg, which acts on some constituent of the 

 egg-cytoplasm, then a rise in conductivity may occur as the result of 

 the liberations of ions from un-ionized substances, while a reversal of 

 this reaction will have an opposite effect. 



Effect of Radium-rayed Sperms on Trout Ova.§— K. Oppermann 

 gets results similar to those obtained in regard to frog's ova by 0. and 

 G. Hertwig. The spermatozoa exposed to radiations produce abnor- 



* 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. 



f This section includes not only papers relating to Embryology properly so 

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

 allied subjects. % Journ. Marine Biol. Assoc, x. (1913) pp. 50-59. 



§ Arch. Mikr. Anat., lxxxiii. (1913) 2te Abt., pp. 141-89 (3 pis. and 10 figs.). 



