LACTATION 603 



the operated animal, an intense glycosuria is said to have occurred, 

 the phenylhydrazine test showing that the substance present in the 

 urine was glucose, and not lactose or some other reducing body. 

 Porcher also removed the mammary glands from four goats and one 

 cow during lactation, and for a few hours after the operation obtained 

 marked glycosuria. As a result of these experiments, taken in 

 conjunction with those of Bert, he concluded that the truth of the 

 latter's theory was established beyond all doubt. 



More recently the writer, working in conjunction with Dr. 

 Kirkness, 1 carried out a series of experiments upon guinea-pigs. 

 The mammary glands were removed prior to pregnancy (four cases) 

 or during pregnancy (one case). The urine was tested for sugar 

 both before and after parturition, but none was found in any of the 

 experiments. Other experiments showed that glycosuria may occur 

 after parturition in normal unoperated animals, but that it does 

 not do so invariably. 2 When glycosuria does so take place, its 

 occurrence is probably comparable to post-operative glycosuria, the 

 cause of which is not understood. The glycosuria observed by 

 Porcher after the removal of the mammary glands during lactation 

 may perhaps be explained as an ordinary post-operative effect, and 

 cannot be cited as proof of Bert's hypothesis. 



According to Thierfelder 3 and Landwehr, 4 a formation of lactose 

 may take place if pieces of fresh mammary tissue are kept in normal 

 salt solution at body temperature. The lactose is said to be formed 

 from a precursor which Landwehr identified as " animal gum " or 

 carbohydrate of low reducing power. 



According to Foa, there is a diminution of glucose in the venous 

 blood coming from the mammary glands, but the amount of glucose 

 and other carbohydrates present in the blood during lactation is no 

 greater than in normal blood. 5 



Muntz 6 has put forward the view that the lactose of the 



1 Marshall and Kirkness, " On the Formation of Lactose," Biochem. Jour., 

 vol. ii., 1906. 



2 Puerperal glycosuria and lactosuria have been described in women in 

 a number of cases. Lactosuria is also stated to occur not infrequently in the 

 late stages of pregnancy both in women and animals, the lactose in such cases 

 being presumably derived from the mammary glands by a process of absorption. 

 So similarly lactose has been found in the urine of cows having accessory glands 

 and teats from which the milk is not drawn off (see above, p. 587 ; Mackenzie 

 and Marshall, MS. unpublished). See Hofmeister, " Ueber Laktosurie," Zeitsch. 

 f. physiol, Chem., vol. i., 1887 ; Porcher, De la Lactosurie, 1906 ; and " L'Origine 

 du Lactose," Arch. Internat. de Phys., vol. viii., 1909. See also p. 539. 



3 Thierfelder, "Zur Physiologic der Milchbildung," Pfliiger's Arch., vol. xxxii., 

 1883. 



4 Landwehr, "Ueber die Bedeutung des tierischen Gummis," PJliiger's 

 Arch., vol. xl., 1887. 



5 Foa, "Sull' Origine del Lattosio del Latte," Arch, di Fis., vol. v., 1908. 



6 Muntz, " Sur 1'Existence des Elements du Sucre de Lait dans les Plantes," 

 Annales de Chim. et de Phys., vol. x. 



