4O NORMAL HISTOLOGY. 



TECHNIQUE. 

 b. INTERCELLULAR SUBSTANCE. 



Fibres of Subcutaneous Connective Tissue. To study 

 these, the skin should be reflected back from the abdomi- 

 nal wall of a recently killed animal (mammal) and choos- 

 ing a part which is free from fat, a bit of the loose, 

 so-called areolar tissue is seized with the forceps and 

 snipped off with scissors. The bit of tissue, which will 

 contract to a little lump around the point of the forceps 

 is to be spread out very thin on a slide and covered with 

 a three-fourth-per-cent. salt solution. The specimen will 

 be seen to consist largely of fibrillated fibres crossing 

 one another in all directions, with a few delicate elastic 

 fibres. After studying in salt solution, a drop of two-per- 

 cent, solution of acetic acid should be allowed to run 

 under one edge of the cover-glass, the salt solution being 

 drawn off by a bit of filter-paper placed at the opposite 

 edge, and the effect carefully observed. This preparation 

 is not to be preserved. 



Fibrillce in Tail Tendon of Mouse. It is not easy in 

 studying fresh tissues to convince one's self that the longi- 

 tudinal striations on the fibres are really the expression 

 of their fibrillar structure, since any attempt to pick the 

 fibres apart with needles is of little avail, because the 

 fibrillae are bound together by a small amount of cement 

 substance. If, however, the tissue be placed for a few 

 hours in some fluid which dissolves this cement substance, 

 as osmic acid, the ultimate elements, the fibrillae, may be 

 readily separated. A bit of the tail tendon of a mouse, 

 or a small tendon from any mammal, should be soaked 



