128 URINE OF COLD-BLOODED ANIMALS. 



CHAPTER X. 



URINE OF .COLD-BLOODED ANIMALS. 



I have always found it very difficult to obtain specimens of the urine of Fishes, 

 for examination. Their bladders are almost always empty. I am enabled, how- 

 ever, to furnish the following qualitative analysis of the urine of the Bass-fish 

 or Red Fish (Corvina ocellata) : — 



Uric acid. Phosphate of magnesia. 

 Oxalate of lime. " of soda. 



Phosphate of lime. Chloride of sodium. 

 " of ammonia. 



When the urine was spread upon a glass slide, and allowed slowly to evaporate, 

 under a magnifying power of 210 diameters, there appeared lozenge-shaped and 

 hexagonal crystals of uric acid, dumb-bell and octohedral crystals of oxalate of 

 lime, and prismatic crystals of triple phosphate. 



The urine of Reptiles resembles that of Birds, not only in appearance, but also 

 in chemical constitution — being only a little more solid when first discharged. Here 

 we have the urine of two wholly dissimilar classes, alike in all respects. 



Birds have a high temperature — in many cases 10° above that of Mammals. 

 Their blood circulates with rapidity, and receives an abundant supply of oxygen. 

 They are also very active in their habits. 



The temperature of Reptiles is not constant; it varies with that of the surround- 

 ing medium. Respiration is imperfect — their lungs being, in most cases, simple 

 sacs — around the walls of which ramify the bloodvessels. Their circulation is 

 sluggish and imperfect, and their habits indolent and inactive. Would any one 

 suppose, h priori, that the secretions of these two classes would be similar? If the 

 explanation be true, that the production of urate of ammonia, in serpents, is due 

 to their imperfect respiration and consequent incomplete oxygenation of the blood 

 and tissues, why should we have the same state of things existing in birds, which 

 have oxygen supplied in large quantities, not only by their lungs but also through- 

 out the tissues, by means of their porous bones ? It is, however, useless to specu- 

 late upon this subject, in the present state of our knowledge. 



The following is a qualitative analysis of the urine of the Coachwhip Snake 

 {Psammoplds flagelliformis) , which I made during the month of July. 



When the urine was allowed to stand for a short time, it formed a hard, white 

 mass, which might have been readily mistaken for so much chalk. Under a magni- 

 fying power of 210 diameters, it was seen to consist of a conglomeration of innu- 



