FIRST DIVISION. 



THE SIMPLE HISTOLOGICAL ELEMENTS. 



THE various structural forms presented to the histologist in the 

 solids and fluids of the human tody may be included under the 

 five following heads: 



I. Homogeneous substance. 

 II. Simple membrane. 



III. Simple fibre. 



IV. Cells. 



Y. The tissues proper. 



All these are developed from the elements in the blood which 

 are required for their nutrition, and in a manner to be described in 

 connection with each. 



The four first mentioned of the preceding forms constitute the 

 simple histological elements, or elements of which the proper tissues 

 are directly or indirectly formed, and will be first of all considered. 



CHAPTEE I. 



HOMOGENEOUS SUBSTANCE. 



BY this is meant a more or less solid, structureless substance, 

 which enters into the composition of several of the tissues. In a 

 thin section it resembles a mere layer of solidified albumen. 



It often fills up the spaces between the fibres or the cells of com- 

 pound tissues ; e. g. cartilage and fibro-cartilage. Consequently it 

 may constitute a large part of the mass of certain tissues. Of pa- 

 thological epigeneses, it exists in cancer, sometimes forming a large 



