VAKIATKJXS IN I'OWS MILK 31 



is abuudant, the milk is generally a little less rich in 

 solids and especially in fat than it is later when the 

 secretion begins to fall off ; with some cows the differ- 

 ence is not very great, but with others it is considerable. 

 In the last month the secretion falls off rapidly and 

 often ceases entirely; at the same time the proportion 

 of solids usually increases and this is especially the case 

 in relation to fat. The milk gradually accjuires a decided 

 alkaline reaction to litnms paper and not infreiiuently 

 develops a salty taste. The changes in composition 

 are shown in the following table, which gives the results 

 of analyses, made by P^leischmann, of the milk of one 

 cow which calved January L'Stli. 



With this cow, the percentage of fat during the 

 ]>eriod of lactation I'ose from .'!.().'!.'! to s.;;iiii; Jnit this 

 significant increase occurred almost entirely iu the last 

 month when the cow had become an old milker. At the 

 same time the (luantity of albumin, lactose and salt 

 {i.r., solids not fat) increased only from S.14 per cent, 

 to 9.00 j.er cent. 



The chemical comjiosition of milk of some cows <lot's 

 not change noticeably during the whole period of lac- 

 tation, and the jjcrcentage of fat as well as the otlu'r 

 solids nmy even fall off a little at the end of the lactation 

 period. Fleisclnnann gives a table showing analyses of 

 the milk of such a cow for the whole lactation period: 

 the daily quantity of milk in April was ID. SI kg., on the 

 :nst of January following it was ;!.(i kg. The fat per- 

 centage, which had varied between 2.56 and 2.97, fell in 

 January to 2.42, 2.(iO. 2.;]2, and 2.4S upon different 

 analyses. The percentage of solids not fat also fell a 

 little. 



7). The time and method of milking. It is commonly 

 believed that there is always a slight difference between 

 the chemical comiiosition of the morning and the even- 



