Milk. 153 



Milk. 



A LECTURE DELIVERED BEFORE THE MONTREAL NATURAL 

 HISTORY SOCIETY. 



By W. Hodgson Ellis, M.A., M.D. 



Milk is the food which Nature has provided for the 

 nourishment of the young of all the higher animals in the 

 first helpless days of their life, before they have learned to 

 forage for themselves. It is to this wonderful fluid — the 

 meat and drink of infancy, a draught of which will satisfy 

 the cravings of the already imperious appetite and still it 

 to a sweet satiety, which a few years later it will seek in 

 vain in a dinner of a dozen courses — to this true elixir vitae 

 by means of which all higher forms of life are perpetuated 

 from generation to generation, that I have the honour of 

 inviting your attention this evening. 



Average cow's milk has a composition about as follows: — 



Fat 3-8 



Albuminoids 4'0 



Milk sugar 4-0 



Salts 0-7 



Water 875 



100-0 

 The fat constitutes butter. 



The greater part of the albuminoids are separated from 

 the milk by the addition of a little acid, either purposely 

 added or formed in the milk itself when it " curdles." The 

 curd carries the fat with it and a portion of the salts. The 

 sugar and the rest of the albuminoids and salts remain in 

 solution in the " whey." On boiling the whey, dissolved 

 albuminoids are coagulated and may be filtered off, and on 

 evaporating the filtrate the sugar crystallizes out. 



That portion of the albuminoids which is coagulated by 

 acid is usually known as casein. The portion not so 

 coagulated is called albumen, and is held by some to be 

 identical with serum albumen. 



If a drop of milk be examined under the microscope it 

 is seen to consist of a clear colourless fluid, in which float 



