GENEEAL ANATOMY, OR HISTOLOGY. 



By E. A. SCHXFER. 



GENERAL ANATOMY, or as it is now more commonly termed HISTOLOGY, is that 

 branch of Anatomy which treats of the structure of the textures. As has already 

 been explained in the Introduction to this volume, the body of every one of the 

 higher animals is made up of organs adapted for the performance of its several 

 functions, and these organs are themselves composed of various tissues or textures. 

 In order that the structure of any organ or part of the body should be understood, it 

 is necessary to study, both together and separately, the several tissues of which it is 

 composed, so as to ascertain their composition and the manner in which they are 

 combined to constitute the organ or part in question. This is chiefly effected by 

 minute dissociations and thin sections, which are observed with the aid of the micro- 

 scope, and hence the terms "Minute Anatomy" and "Microscopic Anatomy" are 

 also applied to this branch of the science. It is found that when the body is thus 

 dissected and analyzed by the aid of the microscope, that the number of distinct 

 tissues which are met with is comparatively small, and some of these again, although 

 at first sight to all appearance distinct, yet have so much in common in their struc- 

 ture and origin one with another (forms of transition also being met with between 

 them), that the number becomes still further reduced. The elementary tissues which 

 may be thus enumerated are as follows : 



The epithelial tissues. 

 The connective tissues. 

 The muscular tissues. 

 The nervous tissues. 



Particles which are met with in the fluids of the body, such as the corpuscles in 

 the blood and lymph, are also described amongst the elementary tissues. 



Many of the organs are formed wholly of a single one of these elementary tissues, 

 or with a comparatively slight intermixture of others. Thus the muscles are made 

 up almost entirely of muscular tissue, with but a small intermixture of connective 

 tissue, blood-vessels and nerves ; whilst the cartilages are composed wholly of a 

 variety of connective tissue. On the other hand, there are certain organs or parts of 

 the body not in themselves distinguished by the preponderance of any special tissue, 

 but compounded of two or more in varying proportion, the structure of which it is 

 nevertheless convenient to describe along with the tissues, on account of their wide 

 distribution in the body, and their uniformity of structure in different parts. Such 

 are : 



Blood-vessels. 



Lymphatic vessels. 



Lymphatic glands and bodies of like structure. 



Serous membranes. 



Synovial membranes. * 



Secreting glands. 



Mucous membranes. 



Integument. 



VOL. i. sr 



