536 SUMMAEY OF CURRENT RESEARCHES RELATING TO 



Influence of Extraneous Forces upon Sex Proportions.* — "W. 



Heape records the results of two sets of breeding experiments with 

 canaries. There is a remarkable difference in the proportion of the 

 sexes of the young birds in the two aviaries, which is consistent both in 

 detail and in the totals. Such consistent variation, when considered in 

 .relation to the food supplied, and to the temperature and surroundings 

 to which the birds w^ere subjected, may be interpreted as evidence of the 

 exercise of extraneous forces on the proportion of the sexes produced, 

 and of selective action on the generative elements dehisced by the 

 parent birds. The factors which mainly governed the results shown for 

 the two aviaries were, for one set (termed G's birds) a temperature and 

 aspect which conduced to early breeding, and the early maturation of 

 ova which had not received specially rich nutrition. The generative 

 functions of these birds were, in fact, " forced " without being richly 

 fed, and they produced males in great excess. Tho other set (termed 

 N's birds) were kept back, they both nested later and moulted later 

 than Ct's birds, their generative functions were not stimulated, the ova 

 matured more slowly and were at the same time more highly fed, and 

 these birds produced a marked excess of females. 



Mendelian Inheritance in Axolotls.f — V. Hacker has, in spite of 

 various draw-backs, succeeded in two sets of experiments in effecting cross 

 breeding between black and white races of AxolotI {Amblystoma 

 tigrinum). In both instances the numerical relations corresponded with 

 surprising exactitude to the Mendelian proportions 3:1. In spite of 

 incomplete prevalence of the dominating character in the first hybrid 

 generation, both races follow in the second generation the law of 

 Mendel, and hence are to be included amongst the few zoological 

 instances where this law can be demonstrated without too great 

 difficulties. 



Brain of Domestic Animals. | — L. Lapicque and P. Girard, from a 

 comparative study of the brains of wild and domesticated types of 

 various species, find that domestication is associated with a diminished 

 brain-weight relative to the total body-weight. 



Fore-brain of Vertebrates.§ — C, U. Ariens Kappers and W. F. 

 Theunissen have investigated the comparative anatomy of the fore- 

 brain in Vertebrates, and in a preliminary paper discuss chiefly the 

 phylogenetic significance of various structures and relations in the brain 

 of Petromyzon, Holocephali, and Selachians. 



Functions of Cerebellum.|| — H. Munk, in a second contribution on 

 this subject, indicates that the specific function of the cerebellum is the 

 more delicate preservation or regulation of balance in sitting, lying, 

 standing, walking, and so on. The activity of the cerebellum stands in 

 relation to these requirements. In the so-called resting stage it in- 

 fluences — like the other central organs of motor apparatus, the cerebrum, 



* Proc. Camb. Philos. Soc, xiv. (1907) pp. 201-5. 



t Zool. Anzeig., xxxi. (1907) pp. 99-102. 



i C.R. Soc. Biol. Paris, Ixii. (1907) pp. 1015-18. 



§ Anat. Anzeig., xxx. (1907) pp. 496-509 (10 figs.). 



II SB. k. Preuss. Akad. Wiss. Berlin, ii. (1907) pp. 16-32. 



