340 SECRETION. 



corpuscles rapidly disappear, and the milk-globules become more abundant, 

 regular and uniform in size. It may be stated, in general terms, that the 

 secretion of milk becomes fully established and all the characters of the 

 colostrum disappear between the eighth and the tenth day after delivery. A 

 few colostrum-corpuscles and masses of agglutinated milk-globules may 

 sometimes be discovered after the tenth day, but they are rare. After the 

 fifteenth day, the milk does not sensibly change in its microscopical or its 

 chemical characters. 



LACTEAL SECRETION IN THE NEWLY-BORN. 



In infants of both sexes there is generally a certain amount of secretion 

 from the mammary glands, beginning at birth or two or three days after, 

 and continuing sometimes for two or three weeks. The quantity of fluid 

 that may be pressed out at the nipples at this time is very variable. Some- 

 times only a few drops can be obtained, but occasionally the fluid amounts 

 to one or two drachms (3'7 or 7'4 grammes.) Although it is impossible to 

 indicate the object of this secretion, which takes place when the glands are 

 in a rudimentary condition, it has been so often observed and described by 

 physiologists, that there can be no doubt with regard to the nature of the 

 fluid and the fact that the secretion is almost always produced in greater or 

 less quantity. The following is an analysis by Quevenne of the secretion 

 obtained by Gubler. The observations of Gubler were made upon about 

 twelve hundred children. The secretion rarely continued for more than 

 four weeks, but in four instances it persisted for two months. 



COMPOSITION OF THE MILK OF THE INFANT. 



Water 894-00 



Caseine 26-40 



Sugar of milk 62.20 



Butter 14-00 



Earthy phosphates . . 1-20 



Soluble salts (with a small quantity of insoluble phosphates) 2-20 



1,000-00 



This fluid does not differ much in its composition from ordinary milk. 

 The proportion of butter is much less, but the proportion of sugar is greater, 

 and the quantity of caseine is nearly the same. 



Of the other fluids which are enumerated in the list of secretions, the 

 saliva, gastric juice, pancreatic juice and the intestinal fluids have already 

 been described in connection with the physiology of digestion. The physi- 

 ology of the lachrymal secretion will be taken up in connection with the eye, 

 and the bile will be treated of fully under the head of excretion. 



Secretory Nerve- Centres. It remains now to consider the influence of 

 nerve-centres upon certain secretions. Cerebro-spinal centres presiding over 

 secretion have not been determined for all of the glands, although they may 

 exist. No cerebro-spinal centres have been described for the secretions of 



