INTBODUCTOKY. 



ENUMERATION OF THE TISSUES AND THE GENERAL 

 STRUCTURE OF ANIMAL CELLS. 



Animal Histology l is the science which treats of the minute struc- 

 ture of the tissues and organs of the animal body ; it is studied with 

 the aid of the microscope, and is therefore also termed Microscopical 

 Anatomy, 



Every part or organ of the body, when separated into minute frag- 

 ments, or when examined in thin slices (sections), is found to consist of 

 certain textures or tissues, which differ in their arrangement in different 

 organs, but each of which exhibits characteristic structural features. 



The following is a list of the principal tissues which compose the 

 body : 



1. Epithelial. 



f Areolar 



j Fibrous 



Elastic 



2. Connective J Adipose 



I Lymphoid 



Cartilage 



Bone 

 ( Voluntary 



3. Muscular j Involuntary or plain 



(Cardiac. 



4. Nervous. 



Some organs are formed of several of the above tissues, others 

 contain only one or two. 



It is convenient to include such fluids as the blood and lymph 

 amongst the tissues, because they are studied in the same manner and 

 contain cellular elements similar to those met with in some of the 

 other tissues. 



The elements which compose the tissues are of the nature either 



1 From i'oT<5s, a web or texture. 



