SUMMARY OF CURRENT RESEARCHES 



RELATING TO 



ZOOLOGY AND BOTANY 



(principally invertebrata and cryptogamia), 



MICROSCOPY, Etc.* 



ZOOLOGY. 



VERTEBRATA. 



a. Embryolog-y.t 



Artificial Parthenogenesis.l — -Yves Delage publishes some notes 

 on a year's experimentation with the ova of Faracentrotus {Strongylo- 

 centrotus) Uvidus. 



Certain substances, toxic in large or medium doses, are, in weak 

 doses, efficacious in assisting the fluids usually employed in bringing 

 about artificial parthenogenesis. Among these fluids, Delage has given 

 preference to one with the following composition : — NaCl, solution 

 2'h n, 87 "5 parts; sea-water, molecular concentration (=0'52/?) 

 2 • 5 parts ; water, GO parts. The efficacy of this is greatly increased 

 by an addition of 5-10 drops per 100 c.cm. of a normal solution of 

 hyposulphite of sodium. Now, if there be added to this a minimal 

 quantity of chloride of manganese, cobalt, or nickel, the parthenogenetic 

 efficacy is greatly augmented. 



There are marked individual differences in the susceptibility of ova, 

 even from the same ovary, and this susceptibility seems to be different 

 in relation to the different reagents, e.g. of nickel and cobalt. 



As to the viability of the parthenogenetic larvas, some progress has 

 been made. Many larvae became plutei. Five showed traces of the 

 young sea-urchin, and in one case the young sea-urchin showed terminal 

 tentacles and two pedicellarise. The countless plutei resulting from 

 normal fertilisation had all died, though reared in identical conditions^ 

 before such an advanced stage was reached. 



♦ 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. J Comptes Rendus, cidiii. (1906) pp. 863-5. 



