EFFECTS OF THIRST, ETC., ON CHELONIANS. 



89 



thrown oft' into the cellular tissue and serous cavities, and discharged by the kid- 

 neys. This shows that there is a tendency to a definite standard of concentration 

 of the blood, and also to a definite proportion of its organic and inorganic constitu- 

 ents, which nature endeavors to maintain, however varied the conditions. 



The effects of a change of diet upon the quantity, and chemical and physical 

 constitution of the excretions of the kidneys, were strikingly illustrated in these 

 experiments. The following table will present this in a clear light. 



From this table we see that the effect of the change of diet was to render the 

 urine much more abundant, and to alter entirely its specific gravity and chemical 

 reactions. 



This subject, however, will be considered in its important bearings, when we 

 come to the investigation of the kidneys and their excretions. 



12 



