bodies, us on the surface of the skin; at other times they become dissolved. 

 UN in some glands; 1'mully, at otlier periods they submit to fatty degeneration, 

 which gradually brings about their complete, destruction. 



The permanent cells have been arranged according to the following 

 denominations : 



1. Hcemalics or red globules, which are found in a state of suspension 



in the blood; they are round or elliptical. 



2. Leucocytes, or white gMmle t which float in the blood, lymph, and chyle. 



3. Connective cells, comprising the connective cell properly so-called, 



the plasmatic cell, and the adipose cell. 



4. Medullary cells, forming the principal elements of the marrow of 



bones (myeloplaxes and rnedullo-cells). 



5. Contractile cells, which constitute the basis of muscular tissue. 



6. Nerve cells, met with in the ccrebro-spinal centres and the ganglia 



of the cerebro-spinal and sympathetic systems. 



7. Epithi'lial cells, comprising the epithelial cells properly called, 



situated on the surface of the skin and mucous membranes, and 

 the glandular cells. 



Fibres. A fibre is an elongated anatomical clement, of variable dimensions 

 and composition. It may be very fine and represented by a single line, or 

 thicker and marked by two lines more or less apart from one another. It 

 is homogeneous throughout, or the contents are distinct from the envelope. 



The vitality of fibres is not to bo compared with that of cells ; after they 

 are formed, they can only bo nourished, and cannot multiply of themselves. 

 In the animal economy four kinds of fibres are distinguished : the connect in 

 fibre, clastic fibre, muscular fibre, and nervous (or nerve) fibre. 



TISSUES. The elements that have now been rapidly described, in 

 becoming united and grouped in different fashions, form the tissues. 



Some tissues are composed of one kind of element ; these are the simple 

 tissues. Example : The epithelium. 



The majority, however, are formed by the union of several different 

 elements : these are the composite tissues. Example : Nervous tissue. 



It is also remarked that there are tissues in which exists a fundamental 

 intcrcelhilar substance, and others in which this is absent. The latter ore 

 few in number, for the vessels and nerves may, in certain tissues, be 

 considered as intercellular substance. 



The anatomical, physico-chemical, and physiological characters of the 

 tissues repeat, as might easily be inferred, the anatomical, physico-chemical, 

 and physiological properties of the elements entering into their formation. 



Only four fundamental tissues are recognised, basing them on the 

 morphological, chemical, and physiological characters of the elements. 



In the first place, the tissue of the n///////7/m/ substance should be noticed ; 

 this, in consequence of some differential characters, may be divided into : 

 ijflatinous tissue, conjunctival (or connective) tissue, cartilaginous tissue, and bom/ 

 tissue. 



Then comes the cellular tissue, formed entirely of persistent cells. It 

 comprises the epithelial tissue and the </t<i minim- tissue. 



The cells of the epithelial tissue may affect different arrangements. If 

 they arc disposed in a single row, there results a siinplf eptthelMM ; if they 

 are superposed it is a stratified epithelium. According to the; form of the 

 cells of the superficial layer, the epithelium is polyhedral, par I-IIK ///. <///;//</,/><//, 

 or ftplurical. In certain points, these superficial cells are furnished with 

 vibrutile filaments; they are then designated ribrnlif ( or ilinlnl ) jiitln-lium. 



