GROWTH OF THE CEREBRAL CORTEX 39 
7. Owing to the greater thickness of the cerebral cortex the 
mature Norway brain contains more gray matter than does the 
albino brain of like weight and this excess of gray matter ex- 
plains the somewhat higher percentage of water found in the 
Norway brain. 
LITERATURE CITED 
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the albino rat in respect to body length, brain weight, spinal cord 
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omy and Biology. No. 6. 
Ferrier, Davin 1886 The funetions of the brain. 2nd ed. Smith, Elder & 
Co., London, pp. 261-262. 
Fortuyn, A. B. D. 1914 Cortical cell-lamination of the hemispheres of some 
rodents. Arch. Neurol., Path. Lab. London County Asyl., vol. 6, 
pp. 221-354. Mus decumanus (Pall), p. 260. 
Lewis, Bevan 1881 On the comparative structure of the brain in rodents. 
Phil. Trans., 1882, pp. 699-749. 
Mitter, Newton 1911 Reproduction in the brown rat (Mus norvegicus). 
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Suarra, Naox1 1917 a Comparative studies on the growth of the cerebral cor- 
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ing the growth of the brain. Albino rat. Jour. Comp. Neur., vol. 28, 
pp. 495-510. 
Suerra, Naoki 1918 Comparative studies on the growth of the cerebral cortex. 
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