242 



TABLE II 



Calculated Values of the Exponent r for the Increase of the Volume 



of the Nerve Cells with the Body Weight 



probably a toj-tenier, of the same body weight, after photographs 

 v\^hich I owe to Prof. W. Leche at Stockholm. The brain weight 

 in the diminutive individual of Domestic Dog, with only a ninth 

 of the mean body weight of the species, is indeed quite 877o 

 more than the mean of the smallest species of Canidae *). The 

 amount and the plus or minus sense of this difference with species 

 is dependent on their body weight. The smaller the species 

 of the genus Oanis, the more it is exceeded in brain weight by 

 an individual of the same size of the Domestic Dog species. 

 Domestic dogs of the size (the body weight) of the common (Euro- 



^) The body weight of a female fennec, killed in its African home, was 1.5 kg. 

 according to Klatt (Studiën zum Domestikationsproblem, p. 36), the weight of 

 the brain was 25.2 g. The capacity of an almost adult female skull in the Leiden 

 Museum of Natural History, observed by me, was 20 c.c, of two other skulls, 

 of which the sex is not indicated, in the Berlin Zoological Museum, the capacity 

 observed by Klatt, is resp. 20 and 18 c.c. When for the species 2 kg. body 

 weight, and 27.9 gr. brain weight is assumed, this gives certainly about the true 

 ratio ; absolutely these weights are possibly estimated too high. From the observa- 

 tions of Klatt (Ibid., Haupttabelle) on 17 adult toy-terriers (Zwergpinscher), of 

 an average body weight of 3.11 kg., with 58.1 gr. brain weight, I calculate for 

 2 kg. body weight of this diminutive breed the brain weight at 52.3 gr. 



