BRAINS OF EUROPEAN AND AMERICAN RATS COMPARED 97 
At some future time it will be of interest to examine the Nor- 
ways of still other countries—those from India for example— 
where we should expect the food conditions to be quite different 
from those obtaining in western Europe and North America. 
5. The capacity of the dried cranium of the rat is modified 
by age and by the amount of calcification to such an extent 
that the data for capacity cannot be transformed into those for 
brain weight without making correction for several fluctuating 
conditions. 
6. The constancy of the foregoing characters in the rats (both 
Norway and Albino) from western Europe and easter America 
indicates that for the purpose of further general studies, the two 
populations may be considered as essentially similar. 
LITERATURE CITED 
Cuisotm, R. A. 1911 On the size and growth of the blood in tame rats. Quart. 
J. of Exper. Physiol., vol. 4, no. 3, pp. 207-229. 
CunnincHaM, D. J. 1909 Text book of anatomy. 3d edition. William Wood 
and Co., New York. 
Donaupson, H. H. 1909 On the relation of the body length to the body weight 
and to the weight of the brain and of the spinal cord in the albino rat 
(Mus norvegicus var. albus). Jour. Comp. Neur., vol. 19, no. 2, pp. 
155-167. 
Donaupson, H. H. and Harai,S. 1911 A comparison of the Norway rat with the 
albino rat in respect to body length, brain weight, spinal cord weight 
and the percentage of water in both the brain and the spinal cord. 
Jour. Comp. Neur., vol. 21, no. 5, pp. 417-458. 
Donatpson, H. H. 1912 On the weight of the crania of Norway and albino 
rats from three stations in western Europe and one station in the 
United States. Anat. Record, vol. 5, no. 2. 
Harat, S. 1907 Studies on the variation and correlation of skull measurements 
in both sexes of mature albino rats (Mus norvegicus var. albus). Am. 
Jour. Anat., vol. 7, no. 4, pp. 423-441. 
Lantz, Davip E. 1909 The brown rat in the United States. U.S. Department 
of Agriculture, Biological Survey, Bull. no. 33, pp. 9-54. 
Watson, CHALMERS 1906 The influence of an excessive meat diet on the os- 
seous system. Proc. Roy. Soc. Edin., 1906-7, vol. 27, part 1, (no. 1). 
