GENERAL CONSIDERATIONS. 3 



not only do they fill certain vessels constructed for them, but they also 

 impregnate all the solid parts of the body. Their importance is very great, for 

 without them the organic solids would perish ; an element deprived of humidity 

 is ipso facto deprived of life. 



These fluids vary in their nature and composition. Apart from those that 

 the solids imbibe, there is not one which is completely amorphous. In the 

 midst of a liquid holding organized matter in solution, there are always formed 

 elements which will be referred to hereafter. Examples : the blood and lymph. 



Organic Solids. — In studying the organic solids, we will proceed from the 

 simple to the complex. 



Solid organized matter is amorphous — as in the hyaline substance of cartilage 

 and the fundamental substance of bone tissue, or it assumes the form of more 

 or less voluminous particles in every instance invisible to the naked eye, and to 

 which the name of anatomical elements has been given. They may be reduced to 

 three principal : the granule, the cell, and the fibre. 



Granules. — These are the smallest known elements. They may be held in 

 suspension in animal fluids, remain free among the other elements, or be enclosed 

 in the interior of cells. Their nature is not always the same : they are proteic, 

 fatty, or pigmentary. The pigmentary granules are of a brown colour. 



Cells. — The cell is pre-eminently the anatomical element. 



Theoretically, the cell is a microscopic mass of a nitrogenous substance, viscid 

 {protoplasm or sarcode), uniformly transparent, or slightly granular. Frequently 

 in the midst of this protoplasm there is perceived a nucleus provided with a 

 nucleolus, and at its periphery an enveloping membrane. 



The cell lives like an entire organism : it feeds, grows, multiplies, absorbs, 

 secretes, moves, etc. It behaves like a complete animal, though it be a micro- 

 scopic one. 



The form of the cell, as well as its volume and nature, vary. It has therefore 

 received various names. 



There are round, polyhedral, fusiform, conical, stellate, and other shaped 

 cells. Some have a diameter of 1-1 2000th part of an inch, while others are 

 l-2000th part. Cells multiply in various ways : 1st, by the division of the 

 nucleus and segmentation of the protoplasm in the interior of the enveloping 

 membrane {endogenous multiplication) ; 2nd, by constriction, then division of the 

 nucleus, protoplasm, and enveloping membrane {flssiparous multiplication) ; 3rd, 

 by a kind of bulging or swelling of the enveloping membrane, and constriction 

 and separation of the enlargement thus formed {gemmation). 



A large number of cells only temporarily remain in this condition. In con- 

 sequence of modifications that cannot be referred to here, they are converted 

 into fibrillse or other elements, in which it is difiicult to recognize the primordial 

 element. 



Others maintain the cellular form : then they develop, live, and die in several 

 ways. Sometimes they are worn by the contact of foreign bodies, as on the sur- 

 face of the skin ; sometimes they become liquefied, as in some glands ; and at 

 other times they undergo fatty degeneration, which gradually brings about their 

 complete destruction. 



The permanent cells are — 



1. Hcematies or red corpuscles, which are found in a state of suspension in the 

 blood ; they are round and discoid in Mammalia, with the exception of the 

 Camel and Llama, in which they are elliptical, as well as in Birds, Reptiles, and 



