72' IMMEDIATE PRINCIPLES OF THE TISSUES. 



irritation of its extremities in the lung, by inhalations of ether or 

 chlorine, produces the same effect, by a reflex action to the liver. 

 Hence we may infer that in diseases of the lungs or medulla ob- 

 longata, diabetes might occur. 



The changes necessary to convert the cane sugar and the dextrine 

 of the food into glucose in the liver have already been stated. 

 Moreover, Bernard has shown that this change is effected by the 

 pancreatic juice in the duodenum. But all thus formed passes from 

 the vena portaB into the hepatic vein, while in the preceding circum- 

 stances it is formed by and in the substance of the liver itself. 



The glucose disappears from the blood by being converted, cata- 

 lytically, into lactic acid (C 6 H 5 5 .HO), which decomposes the car- 

 bonates, and combines with their bases in the blood. But they are 

 soon reconverted into carbonates, and in this form are evacuated in 

 the urine. If there be an excess of sugar in the blood, it will pass 

 off as such in the urine, and perhaps also appear in other secretions 

 already specified. 



2. Sugar of Milk. (C 24 H 24 24 .) 



Synonyms : Lactine ; Lactose. 



This is found only in milk, and in that of all the mammalia. It 

 exists only from some point of time after puberty, continues only a 

 few months at a time, and ceases a few months after the last preg- 

 nancy. In woman's milk it forms 3.2 to 6.4 per cent.; the colostrum 

 containing even 7 per cent. It diminishes in quantity the further 

 the date from the previous delivery; being 5.5 per cent, a few days 

 after delivery, it had fallen to 4.6 per cent, five months from this 

 time. 



It becomes glucose (as does cane sugar) in the liver, and then is 

 finally converted, as before explained, into lactic acid. 1 If this latter 

 change occurs in the milk itself, it becomes acid spontaneously. 



Origin. The parenchyma of the mammary gland fabricates the 

 lactine, as that of the liver does the glucose; from what elements is 

 not precisely known. The longer the milk remains in the breast, 

 the less sugar and other solid principles, and the more water, it con- 

 tains. The kidneys and the lungs are merely eliminators, and not 

 fabricators. 



Taken into the stomach of !he infant, the lactine may be con- 



1 Four atoms of lactic acid equal one of lactine. 



