CHAPTER XIV 



Mode of Secretion of Milk in the Udder 



This subject is still in its infancy so far as it concerns exact knowl- 

 edge of how milk is actually secreted. The subject is, however, 

 important enough for the student of heredity of milk yield to be 

 reviewed by him. For the laboratory exercise, the review of the 

 different original papers on this subject as cited in Chapter V of 

 M . S. by different members of the class together with discussion 

 of the conclusions drawn is suggested. It would also be desirable 

 to have histological sections of udder tissue taken from an animal 

 which had been completely milked out and from another before 

 milking had commenced on demonstration for the students' micro- 

 scopical study. Note should be taken of the size and character 

 of the udder cells and the possibilities of distinguishing cell de- 

 struction versus any other theory, such as the secretion of the milk 

 solids by the cells, to account for the formation of milk by- the 

 udder. The tissue for these sections might be obtained from 

 slaughter houses where milking cows were killed, as for example 

 where slightly diseased tubercular cattle were killed. Care should be 

 taken to have good sections. These may possibly be obtained from 

 the Histology section of the Biology department of the University. 



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