72 HYDROCARBONACEOUS PROXIMATE PRINCIPLES. 



tion of cases, instead of forming a homogeneous solid or fluid with the 

 other proximate principles, the oleaginous matters are* found in distinct 

 masses or globules, suspended in the serous fluids, interposed in the 

 interstices between the anatomical elements, included in the interior of 

 cells, or deposited in the substance of fibres or membranes. Even in 

 the vegetable tissues, oil is always deposited in distinct drops or 

 granules. 



Owing to this fact, the oils can be easily extracted from the organized 

 tissues by the employment of mechanical processes. The tissues, animal 

 or vegetable, are cut into small pieces and subjected to pressure, by 

 which the oil is forced out from the parts in which it was entangled, 

 and separated, sometimes without further manipulation, in a state of 

 comparative purity. A moderately elevated temperature facilitates the 

 operation by increasing the fluidity of the oleaginous matter ; but no 

 chemical agency is required for its separation. Under the microscope, 

 oil-drops and granules can be readily distinguished from the remaining 

 parts of a tissue, and may also be recognized by the dissolving action 

 of ether, which acts upon them, for the most part, without attacking 

 the other proximate principles. 



Oils are found, in the animal body, most abundantly in the adipose 

 tissue. Here they are contained in the interior of the adipose vesicles, 

 the cavities of which they completely fill, in a state of health. These 

 vesicles are transparent, and have a partly angular form, owing to their 

 mutual compression. (Fig. 10.) They vary in diameter, in the human sub- 

 ject, from 28 mmm. to 125 mmm., and are composed of a thin, structure- 

 less animal membrane, forming 



Fig- 10. a closed sac. in the interior of 



which the oily matter is con- 

 tained. The oil, accordingly, 

 is simply included mechani- 

 cally in the interior of the 

 vesicles. Sometimes, when 

 emaciation is going on, the oil 

 partially disappears from the 

 cavity of the adipose vesicle, 

 and its place is taken by a 

 watery serum ; but the serous 

 and oily fluids remain distinct, 

 and occupy different parts of 

 the cavity of the vesicle. 



In the chyle, the oleaginous 

 matter is in a state of emul- 

 sion or suspension in the form 

 of minute particles in a serous fluid. Its subdivision is here more com- 

 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 " molecular base of the chyle." A few of these 



HUMAN ADIPOSK TISSUE. 



