52 



ANNALS NEW YORK ACADEMY OF SCIENCES 



Table XX. — Percentage of ivater in various organs of the dog-fish ivhen the 



animals icere taken from sea-water and after they had been 



immersed in fresh tcater for aljout two hours 



Brain 



Heart 



Kid 



ney 



Spl 



een 



Muscle 



Norm. 



Hypo. 



Norm. 



Hypo. 



Norm. 



Hypo. 



Norm. 



Hypo. 



Norm. 



Hypo. 



Fer ct. 



Per ct. 



Per ct. 



Per ct. 



Per ct. 



Per ct. 



Per ct. 



Per ct. 



Per ct. 



Per ct. 



79.2 



81.8 



81.2 



83.6 



76.6 



82.1 



76.4 



81.0 



74.4 



81.5 



82.9 



82.8 



84.2 



85.3 



81.5 



82.6 



77.2 



31.6 



80.4 



77.8 



81.9 



83.0 



81.0 



84.7 



77.9 



81.6 



77.9 



77.9 



78.7 



78.9 



77.0 



82.0 



80.0 



86.0 



79.8 



82.0 



79.4 



77.8 



77.6 



83.0 



78.9 



83.3 



80.6 



86.8 



97.3 



79.6 



78.6 



82.2 



77.5 



83.9 



81.7 



87.6 



80.6 



85.7 



78.3 



84.0 



78.3 



84.1 



79,7 



82.5 



79.1 



87.6 



79.3 



87.4 



79.6 



86.4 



78.1 



84.3 



80.8 



84.7 



82.3 



86.4 



80.2 



86.2 



79.5 



86.2 



77.6 



81.9 



79.2 



85.1 



80.2 



88.2 



81.0 



97.0 



78.9 



87.4 



77.6 



80.6 



79.1 



77.6 



79.0 



88.3 



81.7 



89.1 



79.7 



85.4 



76.7 



80.6 



78.2 



82.7 



78.7 



81.5 



80.6 



81.7 



78.8 



80.8 



78.5 



71.9 



77.2 



80.2 



79.7 



80.8 



82.0 



82.1 



78.1 



80.8 



78.2 



78.7 



81.6 



80.5 



77.9 



82.1 



80.6 



81.-3 



78.3 



79.7 



78.6 



78.6 



78.7 



82.9 



79.7 



82.3 



80.3 



82.6 



78.2 



82.8 



77.1 



75.6 



85.5 



82.0 



78.3 



81.6 



81.1 



83.5 



82.1 



81.5 



78.3 



80.7 



78.9 



85.3 



75.6 



81.5 



78.9 



83 5 



78.3 



80.7 



77 



80.5 



80 2 



80.5 





81.5 



80.3 



84.2 



78.5 



81.3 



78.5 



80.1 



83.5 



79.1 





81.3 



82.6 



81.6 



79.1 



80.4 



77.3 



79.4 



77.8 



.... 









74.3 



83.7 



75.3 



82.1 



.... 



79.2 











Averages, 79.5 



83.6 



80.5 



84.5 



79.3 



82.5 



77.8 



79.8 



79.4 



81.7 



An examination of the table shows that the organs of the animals that 

 had been immersed in fresh water contain more water than those of nor- 

 mal animals ; the various tissues show the following increases : Brain, 

 4.1 per cent; heart, 4.0 per cent; kidney, 3.2 per cent; spleen, 2.0 per 

 cent; muscle, 2.3 per cent. The average percentage of water in normal 

 tissues was 79.3 per cent, while in the fresh water specimens it was 82.4 

 per cent, an average gain of 3.1 per cent. It thus seems certain that the 

 tissues take up a certain amount of water from the blood, when this is 

 made hypotonic by the immersion of the fish in fresh water. From this it 

 must be concluded that the tissues of an animal constitute a mechanism 

 for the regulation of the osmotic pressure of the blood. 



It was stated above (p. 51) that the kidneys are concerned in the regu- 

 lation of the osmotic pressure of the blood of higher forms. Mammals 

 after drinking a great amount of water secrete a greater amount of urine 

 than usual. This urine is also more dilute than normal urine. Whereas 

 in man urine usually has a specific gravity of 1.020, the dilute urine may 

 have a specific gravity of 1.002 (Hammarsten). Overton found that 

 water absorbed through the skin of the frog is excreted by the kidneys. 



