CHANGES IN COMPOSITION OF BODY OF RAT 37 



Salts. The salts show a slight progressive reduction during 

 the lactation period, after which they increase steadily. 



3. When the chemical composition of several mammals are 

 compared with one another it appears that the bodies of these 

 mammals during growth pass through similar phases of chemical 

 alteration, so far as the water, protein, fat and ash contents are 

 concerned, and that the percentage of water is an indicator of 

 the corresponding phases of the chemical alteration in different 

 species, while neither the calendar age nor body weight of the 

 animals can be used for the same purpose. 



LITERATURE CITED 



Abderhalden, E. 1899 Die Beziehungen der Wachsthumsgeschwindigkeit 



des Siiuglings zur Zusammensetzung der Milch beim Hunde, beim 



Schwein, beim Schaf, bei der Ziege und beim Meerschweinchen. 



Zeit. f. Physiol. Chem., vol. 27. 



1899 Die Beziehungen der Wachsthumsgeschwindigkeit dfes Siiuglings 



zur Zusammensetzung der Milch beim Kannichen, bei der Katze und 



beim Hunde. Zeit. f. Physiol. Chem., vol. 26. 

 Aron, H. 1915 Biochemie des Wachsthums des Menschen und der holieren 



Thiere. Oppenheimer's Handbuch der Biochemie des Menschen 



und der Tiere. Ergiinzungsband, pp. 610-676. Gustav Fischer, Jena. 

 Donaldson, H. H. 1906 A comparison of the white rat with man in respect to 



the growth of the entire body. Boas Anniversary volume. 



1908 A comparison of the albino rat with man in respect to the growth 



of the brain and of the spinal cord. Jour. Comp. Neur., vol. 18. 



1910 On the percentage of water in the brain and in the spinal cord 



of the albino rat. Jour. Comp. Neur., vol. 21. 



1915 Rat Book. Memoirs of The Wistar Institute of Anatomy and 



Biology, no. 6. 

 Koch, W., and Koch, M. L. 1913 A comparison of two methods of preserv- 

 ing nerve tissue for subsequent chemical examination. J. Biol. Chem. 



vol. 14. 

 Koch, W., and Mann, A. 1909 A chemical study of the brain in healthy and 



diseased conditions, with especial reference to dementia praecox. 



Arch. Neurol, and Psychiat., vol. 4. 

 KoNiG, J. 1903 Chemie der menschlichen Nahrungs-und Genussmittel. Band 



1. Julius Springer, Berlin. 

 LowREY, L. G. 1913 The growth of the dry substance in the albino rat. Anat. 



Rec, vol. 7. 

 Mayer, A. and Schaeffer, G. 1914 Recherches sur les constantes cellulaires. 



Te neur des cellules en eau. Jour. Physiol, et Pathol, generale, vol. 16. 

 Pembrey, M. S. and Spriggs, E. I. 1904 The influence of fasting and feed- 

 ing upon respiratory and nitrogenous exchange. J. Physiol., vol. 31. 



