706 SUMMARY OF CURRENT RESEARCHES RELATING TO 



was to be expected, since the markings of such hybrids are not uniform, 

 and the mating was not suitable for bringing out such influence. Guth- 

 rie's results on fowls and Magnus's results on a rabbit give some indication 

 of a " somatic " or " foster-mother " influence in the characteristics of 

 the offspring. 



Artificial Parthenogenesis of Frog's Eggs.* — E. Bataillon made a 

 minute puncture on the eggs of Rana fusca with a fine needle of glass, 

 platinum, or manganese, and a large proportion (three-fourths) seg- 

 mented. About a tenth underwent gastrulation and a few developed 

 into free larvae. It seems that the puncture causes a change in the 

 internal osmotic equilibrium. 



Number of Chromosomes in Batrachians and in Parthenogenetic 

 Embryos.t — Armand Dehorne finds that all the comniou Batrachians 

 have twelve chromosomes, not twenty-four as is usually stated. In the 

 anaphase of the epidermic cells of the larval salamander it is easy to 

 convince oneself that the number is twelve ; in the prophase and uieta- 

 phase twenty-four are seen. 



Dehorne followed Bataillon's method of inducing parthenogenesis by 

 puncturing the eggs of the frog, and he was interested to find that the 

 cells of embryos of 2 days and 6} days had only six chromosomes. 



Intra-uterine Embryos of Saw-fish.} — T. Southwell describes a 

 large saw-fish (Pristis cuspidatus), 15} ft. long, which had twenty-three 

 embryos (nine males and fourteen females) in the oviducts. The 

 embryos all lay horizontally, parallel to the axis of the parent, each 

 about 14 in. long, including a rostrum of 5 in. The dentition on the 

 rostrum was quite apparent, but was entirely covered by a transparent 

 cartilaginous tissue. 



Influence on Nervous System of Extirpation of Limb-primordia 

 in Frog Embryos. § — B. Diirken has made a number of experiments to 

 test whether the development of the appendages influenced the develop- 

 ment of the central nervous system. His results go to show that for a 

 certain period of development there is a correlation. At certain stages 

 a hindering of the development of an appendage is followed by abnormal 

 development in the whole central nervous system. 



Somatic Modifications in White Mice, and their Reappearance in 

 the Offspring.|| — F. B. Sumner, following up his earlier researches, has 

 made a, series of experiments on the effects of differing temperatures on 

 the growth of white mice, with a view to determining whether, and to 

 what extent, these somatic modifications reappear in the offspring. He 

 found that mice which were reared in a warm room (about 21° C.) 

 differed considerably from those reared in a cold room (about r>° C.) 

 as regards the mean length of tail, foot and ear. These organs were 

 found to be longer in the former than in the latter set of individuals. 

 (Differences in hair were not taken into account in this experiment.) 



* Comptes Rendus,cl. (1910) pp. 996-8. t Tom. cit., pp. 1451-3. 



J Spolia Zeylanica, vi. (1910) pp. 137-9 (1 pi.). 



§ Nachr. k. Ges. Wiss. Gottiugen, 1910, pp. 133-40 (5 figs.). 



!| Arch. Entwick., xxx. (1910) pp. 317-48. 



