ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 455 



Vorticella the distinction between somatoplasm and germplasm has 

 begun. The advantage of this is in allowing the somatic functions to 

 continue during conjugation. The relatively large size of ova is inter- 

 preted, in part, in connection with the need for a period of incubation. 

 The introduction of a sedentary habit may have abetted the dimorphism. 



Fertility of Hybrids of American and European Bison. * — E. 

 Iwanoff reports from experiments made at the Zoological Park of 

 M. Falz-Fein, that the hybrids between Bison amerkanus and Bison 

 europeens are fertile. In the case of a male (Bison amerkanus 9 x 

 Bison europseus $ ) the bull would not serve, but one of the testes, 

 which was removed, showed normal spermatozoa in abundance. The 

 hybrid females of the same origin have already borne calves. This is 

 an interesting case, for the species concerned are very distinct. 



State of Ovary in Hybrids of Goldfinch and Canary.! — A. Chapel- 

 lier points out that a female bird may be infertile in various degrees. 

 The ovary may produce no ova ; the ovary may produce eggs which are 

 not laid ; the eggs may be fertilizable or non-fertilizable. He has ex- 

 amined twenty-five hybrids between male goldfinch and female canary, 

 and found various degrees. Some had a rudimentary ovary ; others laid 

 eggs like those of the canary, but smaller. Between these extremes there 

 were inter-grades, e.g. ovaries with very small eggs. Only in about a 

 fourth of the cases did it come to egg-laying. 



Webfoot Character in Pigeons.J — J- Lewis Bonhote corroborates 

 previous breeders in regarding the webbed character as a Mendelian 

 recessive, but the results of mating birds of different webbed strains gave 

 results difficult to reconcile with the Mendelian theory. Each strain by 

 itself breeds true according to Mendel's laws : the disturbing factor is 

 due to the intermixture of the two strains. He is driven back to the 

 suggestion that a factor composed of two parts (cryptomeres), one of 

 which is contained in each strain, causes the web to be suppressed or 

 concealed. 



Action of X-rays on Developing Chick.§— J. F. Gaskell finds that 

 the action of X-rays is to lower the mitotic activity of growing tissues. 

 If this diminution is not too great, complete recovery occurs. If the 

 diminution is above a certain degree, recovery does not take place. The 

 critical dose, which just prevents recovery, varies with the stage of 

 development of the embryo, decreasing as the mitotic index decreases. 

 No other macroscopic or microscopic changes have been observed to take 

 place under the action of X-rays, either in the proportions or structure 

 of the various tissues. 



Lymph-hearts of Turtles. || — F. A. Stromsten has studied the de- 

 velopment of the posterior lymph-hearts in the loggerhead turtle. They 

 are a pair of elliptical pulsating organs situated immediately below the 

 carapace, just behind the upper ends of the ilia. They drain the lymph- 



♦ C.R. Soc. Biol., lxx. (1911) pp. 584-6. f Tom. cit., pp. 328-9 (8 figs.). 



+ Proc. Zool. Soc, 1911, pp. 14-19 (2 figs.). 



§ Proc. Roy. Soc, Series B, lxxxiii. (1911) pp. 305-10. 



|| Anat. Record, v. (1911) pp. 173-8 (3 figs.). 



