224 PROCEEDINGS OF UNITED STATES NATIONAL MUSEUM. 



buried, as it were, in the skin of the abdomen ; as a whole the organs 

 somewhat resemble testicles. According to the information given us, 

 the animal had never given birth to offspring, nor had ever been 

 served by an ass or horse. It appeared that two years before a work- 

 man in the establishment, seeing that the mammae were a little large, 

 attempted to milk the animal, and that the repetition of this act had 

 brought about the condition in which we found the animal. In a 

 moment, and before us, more than four hundred grams of milk were 

 drawn, which issued with much force and fell foaming into the vessel 

 prepared to receive it. When it had remained undisturbed for a little 

 time it appeared of a dead white color, resembling that of milk of 

 almonds. Its odor was slight, not at all resembling that of the mule. 

 Its taste seemed to me oily and a little sweet, but as I tasted of it with 

 repugnance I cannot describe the flavor accurately. Eegarding its 

 other peculiarities I refer to the note of my friend. Professor Fernan- 

 dez. The microscopic characters were those of ordinary milk. 



Such are the more important facts which I learned regarding the 

 hybrid in question. The matter is known to a large number of the cit- 

 izens of Guanajuato. 



The following note on the nature of the mule's milk is extracted 

 from the report of Prof. Vincente Fernandez, which appeared in the 

 same number of the " Eepertorio" in which my own observations were 

 first printed : 



" The liquid obtained from the mule has the appearance of whey, is 

 without sensible odor, and has a sweet taste. Its reaction is slightly 

 alkaline. Density, 1.0270. Heat alone does not coagulate it. Acetic 

 and hydrochloric acids coagulate it, however, and leave oil globules 

 upon the filter. Sulphuric acid coagulates the milk also, and gives a 

 white precipitate by forming an insoluble compound with the casein. 

 It contains, therefore, two of the principal constituents of cow's milk — 

 fats and casein. 



"By pouring into a test-tube 80 drops of pure sulphuric acid, 5 cen- 

 tigrams of ox-besoar,* and a drop of milk, and heating to 60° or 80° 

 F., I obtained a reddish purple color similar to that of a solution of 

 permanganate of potash. This demonstrates the presence of glucose, 

 which is formed by the sulphuric acid at the expense of the lactose — 

 another principle of cow's milk. 



"In order to prove the existence of butter and of casein, I mixed 20 

 centiliters of milk with an equal volume of a saturated solution of sul- 

 phate of soda and one gram of carbonate of soda. 



"Filtration gave a clear liquid, and butter remained on the filter. The 

 liquid, neutralized by acetic acid, gave a precipitate of casein, which the 

 carbonate held in solution. 



*This reagent, very delicate for use iu recognizing the presence of glucose, is a dis- 

 covery of Vicente Fernandez, and has always been of great service to me iu testing 

 diabetic urine. — A. D. 



