SUMMARY OE CURRENT RESEARCHES 



RELATING TO 



ZOOLOGY AND BOTANY 



(PRINCIPALLY INVERTEBRATA AND CRYPTOGAMIA), 



MICROSCOPY, Etc.* 



ZOOLOGY. 



VEBTEBBATA. 



a. Embryology. f 



Carbonic Acid as a Provocative of Artificial Parthenogenesis.^ — 

 Yves Delage finds that the ova of starfish just beginning to show signs 

 of maturation may be induced to develop parthenogenetically by being 

 placed for an hour in sea-water charged with carbon dioxide. It is a 

 simple method to make seltzer water with sea-water, and to put the 

 eggs in it, but the results are astounding. Every precaution to ensure 

 the absence of spermatozoa was taken, and more ova began to develop 

 than if spermatozoa had been supplied. The developing ova formed 

 very vigorous blastulae and gastrulse and characteristic Auricularia-larvae, 

 quite normal and agile. 



Agency of Carbon Dioxide in inducing Artificial Partheno- 

 genesis. § — Yves Delage has shown that the presence of this gas in sea- 

 water may induce parthenogenetic development in starfish (Asterias) 

 eggs. This gas is acid, anaesthetic, and inhibitory to respiration ; and 

 it increases the osmotic pressure of the water. Experiments go to show 

 that it is not in virtue of any of these properties that it induces par- 

 thenogenesis. To say that it acts as a specific stimulant or as an 

 accelerator)' catalytic is merely to use words. A hint is found in the 

 fact that the experiment with C0 2 only succeeds when the ova are sub- 

 jected to the unusual environment just as they are about to exhibit 

 maturation-division or just before the reduced nucleus has passed into 

 a state of rest. The poisonous action of the C0 2 inhibits further pro- 

 cedure, but when the eggs are replaced in ordinary sea- water they recover 

 and go on with their division, it may be on somewhat different lines. 



* 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 tor 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 published, and to 

 describe and illustrate Instruments, Apparatus, &c, 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. 



% Comptes Rendus, cxxxv. (1902) pp. 570-3. § Tom. cit., pp. 605 9. 



