THE SECRETION OF MILK. 193 



tion of tlie blood. In some animals this process apparently 

 goes on with less loss than in others ; but the rapidity with 

 which the elements of food pass on into the circulation of 

 the blood is plainl}^ seen in the shortness of time it takes to 

 show itself in the various secretions of the body. Thus, 

 certain plants or other substances taken into the stomach 

 half an hour previous to milking will perceptibly affect tLe 

 taste and quality of the milk. If you administer a dose of 

 aloes to a horse in the form of a ball wrapped up in paper, 

 and within twenty or twentj'-five minutes after put a bullet 

 through his head, and dissect him, 3'ou will find the paper 

 left in an undigested mass in the stomach ; but you will find 

 traces of the aloes far along at the ver}- mouth of the large 

 intestine. It has dissolved and entered with wonderful 

 rapidity into the circulation of the sj^stem. That has been 

 tried time and time again. It is related, also, t»hat an ox 

 going to the butcher caught up an onion, and ate it. In a 

 very short time he was knocked in the head, when it was 

 found that the onion had tainted the whole body. 



The completeness and economy of this separation of the 

 fatty elements of the food vary according to the internal 

 structure and organism of the animal itself. We cannot, 

 perhaps, tell exactly how this happens ; but the fact is well 

 known. Perhaps it is owing, in part, to the fact that one 

 animal will masticate, or grind up and digest, its food more 

 perfectly than another, and so prepare it to enter more com- 

 pletely into the circulation. 



Now, milk is supposed to be secreted from the blood. I 

 adhere to the commonly accepted theory for the present; but 

 I am not unmindful, of course, that some of the German 

 physiologists, like Ftirstenberg and Voit, take the ground 

 that the formation of milk requires the actual decomposition 

 of the mammary glands themselves, or the substance of the 

 cellular tissue, by which they are transformed into sugar of 

 milk, caseine, &c., with a fatty degeneration. They maintain 

 that milk is simply liquefied cellular tissue, and that it does 

 not depend for its abundant supply upon the quantity or 

 quality of "the blood. They base this deduction on the fact 

 that caseine, which enters so largely into the composition of 

 milk, is not found, as such, in the blood itself, but results 

 from the first process in the decomposition of the gland- 



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