426 : ..FAT.- [BOOK ii. 



be said in favour of the view that the sources of the excess of 

 sugar in the blood may be various, and hence that several dis- 

 tinct varieties of diabetes may exist. In one among many points, 

 the clinical history of diabetes throws light on the possible 

 sources of glycogen. While in many, especially of the less severe 

 cases of diabetes, withdrawal of all amylaceous food is followed 

 by a disappearance of sugar from the urine, in many instances 

 the sugar continues to be discharged even though the diet be 

 perfectly free from carbohydrates ; and in many other cases the 

 sugar in the urine is far in excess of the quantity which might be 

 derived from the food. In these cases the sugar must have some 

 non-amylaceous source ; from this we infer that glycogen also may 

 have a similar origin. And the fact that the urea is increased 

 (and that too in some cases in ratio with the sugar) in diabetes, 

 suggests that the sugar may arise from proteids which have been 

 split up into a nitrogenous (urea) and a non-nitrogenous moiety, 

 and so points out the way in which proteids may be a source of 

 glycogen. 



As a sort of converse of diabetes we may mention that the 

 administration of arsenic in sufficient doses or for an adequate time 

 prevents an accumulation of glycogen in the liver and apparently 

 in the body generally, whatever be the diet used. 



The History of Fat. Adipose Tissues. 



Of all the tissues of the body adipose tissue is the most fluctu- 

 ating in bulk; within a very short space of time a large amount of 

 adipose tissue may disappear, and within an almost equally short 

 time the quantity present in a body may be several times multi- 

 plied. Histological inquiries teach us that when an animal is fatten- 

 ing the minute drops or specks of fat normally present in certain 

 connective-tissue corpuscles (either of a special kind, or certain 

 individuals of the ordinary kind) are seen to increase in number, 

 the protoplasm enlarging at the same time. As these specks 

 increase they coalesce into drops, which by similar coalescence 

 form larger drops, until, the protoplasm first ceasing to increase 

 and then diminishing, the original connective-tissue corpuscle is 

 transformed into a fat-cell, with a remnant only of protoplasm 

 gathered about the nucleus and forming an imperfect envelope 

 round the enlarged contents. When, on the contrary, an animal is 

 fasting, the fat seems in some way or other to escape from the cell, 

 which it may leave as a bag either filled with serous fluid or 

 empty and collapsed around the nucleus. These facts point to 

 the conclusion that the fat of adipose tissue is not simply and 

 mechanically collected in the cell, but is formed by the active 

 agency of the cell, being apparently the result of a breaking up of 



