168 LIPOMATA. 



my reason, lie may find an additional motive for conforming to 

 my view in tins second bond of nnion between the two forms. 



b. Lipomata or Fatty Tumouvs. 



§ 133. Not only is the lipoma or fatty tumour principally 

 made up of the characteristic elements of adipose tissue, the 

 fat-cells, but it also agrees in structure with the normal fat of 

 the human body by the union of these fat-cells into little 

 spheroidal clusters which are parted from one another by septa 

 of connective tissue. A stouter coat of connective tissue com- 

 bines several such clusters into a lobule, also of globular shape ; 

 and it is of such lobules that most fatty tumours appear to the 

 naked eye to be made up. The ■pannkulus adiposus also exhibits 

 a lobulated structure, but its lobules (the fjlandulce adiposce) never 

 reach the considerable dimensions which are commonly attained 

 by the single lobules and tubera of a fatty tumour. The indi- 

 vidual fat-cells of a lipoma differ in like manner from ordinary 

 fat-cells. They are considerably bigger, i.e. more distended with 

 oily matter, which in its turn is more fluid, and contains more 

 elain than usual. 



All the lipomata are perfect examples of central growth. 

 Their enlargement, as well as their origin, depend in the last re- 

 vsort upon an abnormal production of new clusters of fat-cells ; this 

 is brought about by a moderate and sharply-defined proliferation 

 of the connective tissue, leading to the formation of a circum- 

 scribed corpuscular aggregate, followed by an infiltration of the 

 newly- formed cells with oily matter. It would seem however, 

 that the formative stimulus is most intense amid a collection of 

 pre-existing clusters ; while it is certain that the vessels of the 

 new clusters originate from the vessels of the older ones in the 

 same way as do the vessels of papillomata. This explains why 

 a lipoma is usually connected with neighbouring parts at one 

 point only by a stout vascular pedicle, and has the rest of its 

 external surface limited by a large-meshed connective tissue, 

 or even by a smooth capsule ; this explains its peculiar, lobulated 

 build — in a word, the central growth of the tumour. 



Lipomata occur by preference in those localities which are 

 normally infiltrated with fat, such as the subcutaneous, sub- 

 mucous, subsynovial, subserous, subfascial, intermuscular, and 



