CH. IV.] 



AREOLAR TISSUE. 



of many animals, e.g., the frog, and in the choroid coat of 



the eyeball. 



Fig. 55 shows a highly magnified view of a small piece of 

 subcutaneous tissue, and illustrates the irregular way in which 

 the fibres and cells are intermixed. 



Fig. 52. Horizontal preparation of the cornea of 

 frog, stained in gold chloride; showing the 

 network of branched cornea corpuscles. The 

 ground substance is completely colourless. 

 X 400. (Klein.) 



Fig. 53- Ramified pigment- 

 cells, from the tissue of 

 the choroid coat of the 

 eye. x 350. a, cell with 

 pigment ; b, colourless 

 fusiform cells. (Kolli- 

 ker.) 



Fig. 54. Flat, pigmented, branched connective-tissue cells from the sheath of a large 

 blood-vessel of the frog's mesentery ; the pigment is not distributed uniformly through- 

 out the substance of the larger cell, consequently some parts of it look blacker than 

 others (uncontracted state) . In the two smaller cells most of the pigment is withdrawn 

 into the cell-body, so that they appear smaller, blacker, and less branched. X 350. 

 (Klein and Noble Smith.) 



We have now to consider the undifferentiated intercellular 

 material which is called 



The ground-substance. This may be represented in fig. 5 5 by 

 the white background of the paper. 



It may be readily demonstrated in a silver nitrate prepa- 

 ration ; for the intercellular material has the same property of 

 reducing silver salts in the sunlight that the cement-material 



