90 



PROXIMATE PRINCIPLES OF THE SECOND CLASS. 



Fig. 9. 



HUMAN ADIPOSK TISSUE. 



of health. These vesicles are transparent, and have a somewhat 

 angular form, owing to their mutual compression. (Fig. 9.) They 



vary in diameter, in the hu- 

 man subject, from 5^ to .j^ 

 of an inch, and are composed 

 of a thin, structureless ani- 

 mal membrane, forming a 

 closed sac, in the interior of 

 which the oily matter is con- 

 tained. There is here, accord- 

 ingly, no union whatever of 

 the oil with the other proxi- 

 mate principles, but only a 

 mechanical inclusion of it in 

 the interior of the vesicles. 

 Sometimes, when emaciation 

 is going on, the oil partially 



_. c J 



disappears from the cavity of 

 the adipose vesicle, and its place is taken by a watery serum ; but 

 the serous and oily fluids always remain distinct, and occupy differ- 

 ent parts of the cavity of the vesicle. 



In the chyle, the oleaginous matter is in a state of emulsion or 

 suspension in the form of minute particles in a serous fluid. Its 



subdivision is here more com- 



Fi 8- 10 - plete, and its molecules more 



minute, than anywhere else 

 in the body. It presents the 

 appearance of a fine granular 

 dust, which has been known 

 by the name of the " molecu- 

 lar base of the chyle." A 

 few of these granules are to 

 be seen which measure J-GVVV 

 of an inch in diameter ; but 

 they are generally much less 

 than this, and the greater part 

 are so small that they cannot 

 be accurately measured. (Fig. 

 10.) For the same reason 

 they do not present the bril- 

 liant centre and dark border of the larger oil-globules; but appear 



H T i, E , from 

 from tjie Dog. 



commencement of Thoracic Duct, 



