VESSELS AND LYMPHATICS 



39 



Throughout life growth continues, and in the adult animal 

 is on the average 2.2 mm. per week in the upper and 2.8 mm. per 

 week in the lower incisor. 



In a five months animal the thickness of the enamel and its 

 constituent layers measured in the mid-line of the teeth is given 

 in table 15. 



Measurements of the incisors and skulls of animals of different 

 ages were made and are shown in table 16. 



The lower incisor of a five months animal forms a segment of 

 about four-fifths of a semicircle (140-145). 



4. Muscles. Morpurgo (1898) has furnished data on the Muse. 

 radialis of the albino rat; giving the number of muscle fibers and 

 of nuclei at different ages (table 17). 



TABLE 17 



5. Vessels and lymphatics, a) Blood. Specific gravity 1.056 

 (Sherrington and Copeman, 1893). The diameter of the erythro- 

 cytes is as follows (White, '01) : 



FOR M. DECUMANUS 



DIAMETERS 

 IN It 



1} Percentage of water in the blood. Hatai (MS '15) has deter- 

 mined the percentage of water in the blood of a small series of 

 Albinos. 



