Urinary Secretion of certain Animals. 49 



position, must it not be considered, having the functions of a 

 urinary bladder, to be such in reality 1 Moreover, apart 

 from the chemical composition of the fluid, it appears to me 

 difficult to conceive how, on the supposition of absorption (the 

 ground on which the other physiologist supports his opinion),* 

 it can find its way into the bladder, inasmuch as this organ 

 is provided with few bloodvessels from which an inhalation 

 can take place ; nor does it appear to possess the pi-operty of 

 imbibition or endosmosis, by which fluid could be drawn into 

 it from the cavity of the abdomen ; for when immersed in wa- 

 ter, empty and collapsed in situ, immediately after the deca- 

 pitation of the animal, it does not become distended. 



Before concluding, I would make one remark, which is, 

 that though I believe the quality of the secretion of the kid- 

 neys to depend chiefly on structure, I am also of opinion that 

 this secretion is affected, in a minor degree, by circumstances 

 of diet, and of atmospheric temperature, and especially in 

 man. In a cold or cool climate, using a diet chiefly of ani- 

 mal food, lithic acid and lithate of ammonia are found com- 

 monly, in a vegetable proportion, in the human urine ; but 

 not so in a hot climate, not even when the diet is the same ; 

 and, in consequence, within the tropics, where least oxygen 

 is consumed in respiration, the ailments depending on the 

 formation of gravel and calculi are almost unknown. In the 

 instances of other animals, no doubt, the proportion of the 

 urinary matter, the quantity secreted, depends very much on 

 the quantity of food taken ; and, when, as in some instances, 

 it is a mixture of animal and vegetable matter, and the ui-ine 

 secreted is semifluid or concrete highly azotised matter, as in 

 some birds or insects, it depends also on the quantity of the 

 former that is consumed. 



Baubadoes, September 6, 1847. 



* Professor Bell, in article Amphibia , Cyclopaedia of Anatomy and Physiology, 

 p. 104. 



VOL. XLIV. NO. LXXXVIl. — JAN. 1848. 



