156 SUMMARY OF CURRENT RESEARCHES RELATING TO 



acceleration induced by the introduction of a foreign nuclear element). 

 After electric shocks the eggs become non-fertilizable, but they will 

 develop abnormally and form larva? if they are inoculated with a cata- 

 lysing nucleus. Mere pricking them is not efficacious. The efficacy of 

 the second faction (the introduction of a foreign nuclear element) seems 

 to be limited to the first hour after activation. The change of state 

 produced by activation is independent of the afflux of water. Internal 

 movements may be seen going on in the ova in a moist chamber just as 

 in those in immersed ova. 



Eggs of Rana fusca, exposed to vapour of chloroform in a moist 

 chamber for three minutes, are activated as others are by electricity. 

 They are non-fertilizable. They give off their second polar body and 

 divide. If they are moistened with blood and then pricked they 

 develop into larva?. The same result may be obtained by using vapour 

 of ether, benzol, and toluol. After the activation there has to be an 

 introduction of some organic apparently nuclear matter, which Bataillon 

 regards as having a catalytic influence. 



Various physical and chemical excitations (electric discharges, 

 changes of osmotic pressure, exposure to vapours, etc.) affect the ovum, 

 and are followed by a reaction which opposes a barrier to fertilizing 

 elements. The addition of a catalysing nucleus to the ovum in its new 

 state of equilibrium is followed by embryogenesis. 



Artificial Parthenogenesis in Frog.* — Fritz Levy has reared not 

 only tadpoles, but three young frogs from artifically stimulated eggs. 

 His method was to prick the eggs with a platinum needle, which was 

 sometimes first dipped in salt or in the blood of the mother. He finds 

 that the nuclei of the results of this aspermic development are smaller 

 than the normal, and he believes that they are haploid, i.e. with half 

 the normal number of chromosomes. 



Artificial Parthenogenesis in Frog and Toad. f — Giinther Hertwig 

 finds that eggs of Rana esculenta and Bufo vulgaris fertilized by sperms 

 of Rana fusca segment normally, but die before gastrulation. But if 

 the sperm of R. fusca be first exposed to intense radium rays, and then 

 used for fertilization, the eggs go through gastrulation and become 

 larva?, which survive for several weeks. The explanation suggested of 

 this paradox is that the sperm of R. fusca contains some chromatin 

 element which is not in harmony with the idioplasm of the ova of 

 R. esculenta or Bufo vulgaris ; therefore the developing ova soon die. 

 But if this element be destroyed by the radium, the sperm may act 

 simply as a stimulus to development — which is really parthenogenetic. 

 In various organs, it is noticed, the surface or the volume of the nuclei 

 is half the normal. 



Hermaphroditism in Toad.J — 0. Fuhrmann describes a number of 

 cases of hermaphroditism in Bufo vulgaris — several of rudimentary 

 hermaphroditism affecting the gonads and their ducts, two of potential 



* Arch. Mikr. Anat., lxxxii. (1913) 2te Abt. , pp. 65-77 (8 figs.). 



t Arch. Mikr. Anat., lxxxi. (1913) 2te Abt., pp. 87-127 (2 pis. and 6 figs.). 



J Rev. Suisse Zool., xxi. (1913) pp. 331-45 (6 figs.). 



