6o2 THE PHYSIOLOGY OF REPRODUCTION 



nothing more than an emulsion of the fat of butter in a solution of 

 salts, proteins, and sugar. " What occurs as a normal process in the 

 cells of the lacteal glands occurs under pathological conditions in 

 much greater extent in very various tissues, and leads almost always 

 to incurable and fatal losses, since as a rule no reparation is made by 

 the younger cells." ^ " The production of milk," says Virchow,^ " in 

 the brain instead of in the lacteal glands, constitutes a form of brain 

 softening. The same process that in the one place affords the 

 happiest and sweetest results, in another induces a painful and bitter 

 wound." It has already been mentioned, however, that the fat of 

 milk' has a special composition of its own, so that too much stress 

 must not be laid upon a resemblance between the secretion of milk 

 and the pathological formation of other fluid substances in different 

 parts of the body. 



The mode of formation of. the sugar of milk has been the subject 

 of some controversy. Bert^ supposed that it was fornied from 

 glucose which was absorbed by the cells of the mammary gland 

 from the circulating blood. The glucose, according to this view, was 

 manufactured in the liver, or, at any rate, elsewhere than in the 

 mammary gland. Bert based his hypothesis upon two experiments 

 in which the glands were removed from goats which afterwards 

 became pregnant. The urine of each animal was tested during 

 pregnancy to see if any reducing agent was present, but no such 

 substance could be found prior to the birth of the kid. On the 

 other hand, for several days after parturition a substance which 

 reduced cupric sulphate was discovered in each case. Bert concluded 

 that this was glucose. He supposed further that the reducing body 

 present in the urine of the two goats represented glucose which in 

 normal animals would have been converted into lactose in the 

 mammary glands. The experiments were afterwards repeated by 

 Moore and Parker,* who operated likewise upon two goats, and 

 obtained results which were the direct opposite of those of Bert. 

 These authors consequently concluded that the complete process of 

 lactose formation takes place in the cells of the mammary glands. 



The question was subsequently reopened by Porcher,^ who also 

 repeated Bert's original experiment on a goat. After parturition in 



• Verworn, General Physiology, Lee's Translation from the -second German 

 edition, London, 1899. 



2 Virchow, loo. cit. , 



^ Bert, "Sur I'Origine du Sucre du Lait," C. R, de I'Acad. des Sciences, 

 voL Ixxxviii., 1884. 



* Moore (B.) and Parker, " A Study of the Effects of Complete Removal of the 

 Mammary Glands in Eelationship to Lactose Formation," Amer. Jow. of 

 Physiol., vol. iv., 1900. 



° Porcher, "Sur I'Origine du Lactose,'' C. R. de I'Acad. des Sciences, 

 vol. cxxxviii., 1904. "De la Lactosurie," Monographies Cliniques, Paris, 1906. 



