I. HISTOLOGY OF THE HUMAN BODY. 



ORGANS on minute examination are found to be made up of 

 tissues, or elementary tissues as they are sometimes called. 



Of elementary tissues there are four: 1. Epithelial; 2. Con- 

 nective ; 3. Muscular ; and 4. Nervous. 



Some organs contain all four kinds of tissues, while others, 

 more simple in their structure, contain but one or two. 



If these tissues are still further analyzed, they are seen to con- 

 sist of cells or fibers, or of both together in varying proportions : 

 thus the epithelial tissues are made up of cells alone ; the con- 

 nective tissue, principally of fibers ; and the nervous, of both cells 

 and fibers. 



Cells (Fig. 1). A cell consists of protoplasm, a nucleus, and 

 a centrosome and attraction-sphere. A cell-membrane enclos- 



Chromatin network 



Linin network 

 Nuclear fluid 



Nuclear membrane.'. ^2 



Cell-membrane. 



Exoplasm. j 



Spongioplasm. 

 Hyaloplasm. 



Nucleolus 

 Chromatin net-knot. 



JJ Centrosome. 

 Centrosphere. 



Foreign mclosures. Metaplasm. 

 FIG. 1. Diagram of a cell (Huber). 



ing the protoplasm may or may not be present ; it is not an 

 essential part of a cell as are the other structures. A centrosome 



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