46 THE TISSUES. [CHAP. I. 



simplest form which animal matter assumes in its organization is 

 that of a nucleated cell. Such cells exist in vast numbers, free 

 and isolated, floating in the blood, but having occasionally a re- 

 markable tendency to cohere. These are the red particles of the 

 blood, which perform some very important office in reference to 

 that fluid and the different tissue*, as appears from the serious 

 results consequent upon a great deficiency of them. They may be 

 considered to be among the simplest products of organization. 



In the embryonic state all the tissues are composed of cells, 

 analogous in structure to the corpuscles of the blood. These 

 are united together by a more or less abundant intercellular sub- 

 stance, which is either homogeneous (hyaline), minutely granular, 

 or indistinctly fibrous. Some tissues retain, as their permanent 

 character, this cellular structure; whilst in others the cells un- 

 dergo certain metamorphoses by which they are converted into 

 other forms, which constitute the anatomical elements of the 

 adult textures. 



It seems impossible to devise a satisfactory arrangement of the 

 tissues, which shall be based on one principle of classification. The 

 following table has been constructed chiefly with the object of 

 presenting to the reader a general view of the various tissues, the 

 anatomical characters of which will be discussed in subsequent 



TABULAR VIEW OF THE TISSUES OF THE HUMAN BODY. 



1. Simple membrane, homogeneous, or Examples. Posterior layer of the 



nearly so, employed alone, or in the cornea. Capsule of the lens. 



formation of compound membranes. Sarcolemma of muscle, &c. 



2. Filamentous tissues, the elements of White and yellow fibrous tissues. 



which are real or apparent filaments. Areolar tissue. 



3. Compound membranes, composed of Mucous membrane. Skin. 



simple membrane, and a layer of True or secreting glands. 

 cells, of various forms (epithelium or Serous and synovial mem- 

 epidermis), or of areolar tissue and branes. 

 epithelium. 



4. Tissues which retain the primitive eel- Adipose tissue. Cartilage. 



lular structure as their permanent Grey nervous matter, 

 character. 



5. Sclerous or hard tissue. Bone. Teeth. 



6. Compound tissues. 



a. Composed of tubes of homogeneous Muscle. Nerve. 

 membrane, containing a peculiar 



substance. 



b. Composed of white fibrous tissues Fibro-cartilage. 

 and cartilage. 



