154 MMAKV OF OUBBENT RESEARCHES RELATING TO 



Experimentally Induced Parthenogenesis in Toad.* — E. Bataillon 

 has succeeded in indacing segmentation in toads' eggs. A string of 

 egga is placid in a vessel with as little mucus as possible ; it is bathed 

 with blood ; then the eggs are finely punctured; segmentation results. 

 The blood of the frog will serve instead of that of the toad. If the 

 spermatozoa of Ranafwca be used there is amphimixis, but the develop- 

 ment is abortive, and does not reach gastrulation. The blood of 

 R fusca gives better results than the spermatozoa. The blood stimulus 

 "respects the specific nuclear combination"; the inappropriate amphi- 

 mixis disturbs it. 



Artificial Parthenogenesis of Toad's Egg. f — E. Bataillon has 

 induced segmentation by injecting into the eggs some Mammalian 

 1 1 )od, or sperms, or extract of spleen, or carp blood, or extract of testis. 

 The " accelerating principle " introduced need not be specific ; the 



utial conditions are puncture and the introduction of some foreign 

 cellular elements. 



Artificial Parthenogenesis in Toad.}. — E. Bataillon maintains that 

 in the parthenogenetic development that follows puncture there is more 

 than a reaction to the w T ound. The stylet must introduce some foreign 

 body ; even a leucocyte will serve, and the best results are obtained by 

 introducing some blood or the like which acts as an " accelerative and 

 regulative agent." But it is not anything specific that requires to be 

 introduced ; the blood of a fish will do just as well as the blood of a frog. 



Number of Chromosomes in Parthenogenetically produced Larvae 

 of the Frog.§— A. Dehorne has carefully studied eight days' old larvae, 

 and finds that the number of the chromosomes in the somatic cells is 

 si\, which corresponds to half the normal number. 



Plasmic Reduction in Spermatogenesis.!— M. Romieu calls atten- 

 tion to what he calls plasmatic reduction in the spermatogenesis of 

 Ascaris megalocephala. Apart from the chromatin-reduction of the 

 nucleus, there is a reduction of cytoplasm. It is this which effects the 

 true maturation of the spermatozoa. 



Effects of One-sided Ovariotomy on Sex of Offspring. f — L. I)on- 

 caster and P. EL A. Marshall find that in the rat it is not true that ova 

 determining one sex are produced from one ovary, and those determining 

 the opposite sex from the other, for each rat, with one ovary completely 

 removed, produced young of both sexes. The " right and left ovary 

 hypothesis " is not true for the rat at least. 



Origin of Sex.**— Sydney J. Hickson directs attention to the evolu- 

 tion of sex as it is illustrated in Protozoa. In Actinophrys two similar 

 individuals conjugate; in Coccidium there are ovum -like and 

 spermatozoon-like individuals which conjugate : in Paramecium and 



* Comptes Rendus, clii. (1911) pp. 1120-2. \ Tom. cit., pp. 1271-3. 

 \ C.R. Soc. Biol., lxx. (1911) pp. 562-4. 

 § Comptes Rendus, clii. (1911) pp. 1123-4. 

 II C.R. Soc. Biol., lxx. (1911) pp. 412-14. 

 1 Jouxn. Genetics, i. (1910) pp. 70-2. 

 * Trans. Manchester Micr. Soc, 1910, pp. 34-45. 



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