222 OF THE PRIMARY TISSUES OF THE HUMAN BODY. 



the violence of some local affection. In fact, the general tendency of these 

 diseases to the adynamic type, seems to indicate that, however beneficial the 

 immediate results of reducing treatment may appear to be, its remote effects are 

 much to be dreaded. And when the results of a large and varied experience 

 are brought together, the Author believes that those will be found most satis- 

 factory in which the treatment has been moderately evacuant and early susten- 

 tative. 1 



CHAPTER Y. 



OF THE PRIMARY TISSUES OF THE HUMAN BODY; THEIR 

 STRUCTURE, COMPOSITION, AND ACTIONS. 



217. THE elementary Cells, Membranes, and Fibres, of which a general 

 description has been given in a preceding chapter, are combined with each other 

 in various modes, and are subjected to various metamorphoses, to form those 

 different types of Organic Structure, to which the name of Primary Tissues is 

 given. These may be seen to evolve themselves gradually from that homoge- 

 neous mass of cells, of which the fabric of the embryo is originally composed ; 

 each tissue becoming more unlike the rest in structure and properties, as it 

 advances in its development; but yet presenting, even in its most complete and 

 perfected state, no endowments which are not referable to those of the simple 

 primordial cells from which it originated. By this developmental process, in 

 fact, a structure is formed, in which every separate part has a distinct office to 

 perform; and it is this complete "specialization," or "division of labor," which 

 constitutes the highest degree of organization. In every such fabric, however, 

 each part lives, not only for itself, but also for every other part; for this very 

 specialization, whilst it involves the increase of some particular form of vital 

 endowment, involves also the decrease of others ( 113); and hence it comes 

 to pass, that the sum of the operations necessary for the maintenance of the 

 life of even a single cell, in the conditions amidst which Man is placed, can only 

 be performed by the totality of his entire organism, all the parts of which are 

 mutually dependent upon one another. Thus, the life of his Nervo-Muscular 

 apparatus, which may be considered as the most essential part of his fabric, 

 cannot be sustained except by nutritive material prepared and conveyed to it by 

 the organs of Digestion and Circulation, and would soon cease if provision were 

 not also made for conveying away the products of its disintegration, by the 

 various instruments of Excretion; whilst, on the other hand, the appropriation, 

 preparation, and ingestion of food, the sustenance of the respiratory changes, 

 and many other actions essential to the preparation and purification of the 

 pabulum of the Nervo-Muscular apparatus, require the assistance of movements 

 which it alone is competent to execute. As the properties which the Primary 

 Tissues possess in common have been already considered (CHAP, in.), we have 

 now to inquire into those by which they are severally distinguished ; and to 

 trace out, so far as may be, the mode in which their special types of structure 

 and endowment are respectively evolved, from those more general forms in which 

 they all originate. 



1 On the subject of the latter portion of this section, the treatise of the late Dr. Robert 

 Williams on "Morbid Poisons," and the "Principles of Medicine," of Dr. Charles J. B. 

 Williams, may be studied with great advantage. 



