SKIN. 63 



INTEGUMENTS, ETC. 



CELLULAR TISSUE. 



The cellular or areolar tissue is that substance found so universally 

 distributed throughout the body. It serves for the purpose of con- 

 necting muscles and organs, and forming a protection, being parti 

 cularly abundant beneath the skin. When parts are torn in a sub 

 ject it is very distinct, and its characters can then be best observed 

 It will be found to be white in colour usually, and to consist of a num 

 ber of cells which freely communicate, as is manifested in anasarca 

 emphysema, and ecchymosis. It is elastic and tough when fresh 

 when dried it is opaque and crisp ; long boiling converts most of it 

 into gelatine. Its toughness is due to one set of fibres, which are 

 white, inelastic, and straight ; of such most ligaments are formed. 

 Its elasticity IS due to another set of fibres, which are yellow, elastic, 

 and curling ; of such the ligamentum nuchas and middle coat of 

 arteries are composed. 



It is very vascular, though most of its vessels do not contain red 

 blood in health, as may be seen in inflammation produced by the air 

 or any other stimulus. Its moisture is due to serum. 



FAT, 



Fat is found in almost every part of the body, with the exception 

 of the penis, ear, eyelid, and ball, interior of cranium, &c. &c,, but 

 in great abundance under the skin around the serous membranes. 

 It is of a yellowish colour, and in life is in a semi-fluid condition. 

 It consists of three elements, stearine, margarine, and efeine, which 

 are contained in vesicles aggregated in lobules. In women fat is 

 more abundant ; and in infants it is upon the surface of the body, 

 rather than in the cavities. 



It is of use in diminishing pressure upon the hands and feet ; retains 

 heal, being a bad conductor, and assists in nutrition, as is manifested 

 in hibernating animals. 



SKIN, 



The skin is an external covering and protection, as well as an 

 organ of touch and excretion. Its colour and thickness vary in 

 different persons and in different parts of the same person. At the 

 orifices of cavities it is converted into mucous membranes. The 

 largest wrinkles are produced by the contractions of muscles, and by 

 the flexion of joints ; others of an angular variety, owing to the con- 

 tractile character of the skin, are seen upon the back of the hand ; 

 the third variety is spiral. 



The skin i§ perforated by hairs, perspiratory ducts, pits containing 

 sebaceous glands and follicles ; these are considered as ajpioe^idages. 



