EFFECTS OF THIRST — ALBINO RATS 413 



Spinal cord 



The spinal cord, like the brain, sometimes appeared definitely 

 congested at autopsy. In the acute-thirst series the spinal cord 

 shows an apparent increase of 1.8 per cent in average weight, and 

 in the chronic-thirst series a loss of 6.7 per cent (table 2). It is 

 evident that in the spinal cord, as in the brain, there is no appre- 

 ciable change in weight during acute thirst and a slight loss during 

 chronic thirst. The apparent loss of 16.7 per cent in the spinal 

 cord of the rat (Si. 2) on total inanition (table 1) is probably due 

 to an individual variation. Falck and Scheffer ('54) observed 

 an apparent loss of 7.1 per cent in the weight of the spinal cord 

 of a dog kept on dry diet with a loss of 20.7 per cent in body 

 weight. 



Likewise in albino rats after inanition with water, Jackson 

 ('15) noted no significant change in the weight of the spinal cord 

 during acute inanition and a loss of but 4 per cent during chronic 

 inanition. He cited observations of several previous investi- 

 gators who obtained similar results in various animals during 

 inanition with or without water. 



Sciatic nerves 



In order to study the effects of thirst upon the weight of the 

 peripheral nerves, sciatic nerves (nn. ischiadici) on both sides 

 were cut proximally at the exit from the pelvic cavity in the thigh 

 and distally at the middle of the thigh. As seen in table 1, the 

 data show considerable individual variation, so no stress can be 

 laid upon differences between the results. In the acute-thirst 

 series (table 2) the nerves show an apparent loss of 21.3 per cent 

 in average weight, and in the chronic-thirst series a loss of 22.1 

 per cent. This would indicate that during thirst the loss in 

 weight is relatively greater in the peripheral than in the central 

 nervous system. No observations by others upon this point 

 have been found in the literature, but Doctor Hatai has called 

 my attention to the fact that there is a large amount of fat usually 

 present in the normal sciatic nerve. 



