PRIMARY AND COMPOUND TISSUES. 59 



interlacing and leaving between each other areolse or cells. These 

 filaments although possessed, like every other living tissue, of con- 

 tractility or the power of feeling an appropriate irritant and of moving 

 responsive to such irritant do not move perceptibly under the influence 

 of mechanical or chemical stimuli. They are mainly composed of 

 concrete gelatin. The great bulk of animal solids consists of areolar 

 tissue, arranged as membrane. 



2. Muscular fibre or tissue is a substance of peculiar nature ; ar- 

 ranged in fibres of extreme delicacy. The fibres are linear, soft, gray- 

 ish or reddish, and manifestly possessed of contractility or irritability ; 

 that is, they move very perceptibly under the influence of mechanical 

 or chemical stimuli. They are composed, essentially, of fibrin. Their 

 histology will be described hereafter. 



Muscular fibres, which are arranged in the form of membranous 

 expansions or muscular coats, differ from proper muscles chiefly in the 

 mechanical disposition of the fibres. The physical and chemical 

 characters of both are identical. The fibres, instead of being collected 

 into fasciculi, are in layers, and, instead of being parallel, interlace. 

 This tissue does not exist in the zoophyte. 



3. Nervous, pulpy, or medullary fibre or tissue, which will be referred 

 to hereafter, is much less distributed than the preceding. It is of a 

 pulpy consistence ; is composed essentially of albumen united to a 

 phosphuretted fatty matter ; and is the organ for receiving and trans- 

 mitting impressions to and from the nervous centres. Of it, brain, 

 cerebellum, medulla spinalis, nerves and their ganglia are composed. 



Professor Chaussier 1 added another primary fibre or tissue, the 

 albugineous. It is white ; satiny; resisting; of a gelatinous nature; 

 and constitutes tendons and tendinous structures. Chaussier is, per- 

 haps, the only anatomist that admits this tissue. Others properly re- 

 gard it as a condensed variety of the areolar. 



These various fibres or tissues, by uniting differently, constitute the 

 first order of solids ; and these, again, by union, give rise to compound 

 solids, from which the different organs are formed. A bone, for ex- 

 ample, is a compound of various tissues ; osseous in its body; medullary 

 in its interior ; and cartilaginous at its extremities. 



Bichat 2 was the first anatomist who possessed clear views regarding 

 the constituent tissues of the animal frame ; and whatever merit may 

 accrue to after anatomists and physiologists, he is 7 entitled to the credit 

 of having pointed out the path, and facilitated the labours of the ana- 

 tomical analyst. 



The term texture can only apply to solids ; but inasmuch as there 

 are in suspension in certain fluids, as the blood, chyle and lymph, solid 

 corpuscles of determinate form and organic properties, and which are 

 not mere products or secretions of a particular organ, or confined to a 

 particular part, such corpuscles have been looked upon as organized 

 constituents of the body, and therefore considered along with the solid 

 tissues ; and, accordingly, the textures and other organized constituents 

 have been enumerated as follows : 3 



1 Table Synoptique des Solides Organiques. a Anatomie Gn., Paris, 1801, torn. i. 



3 Quain and Sharpey, Human Anatomy, Amer. edit., by Dr. Leidy, i. 39, Philad., 1849. 



