20 



LESSON IX. 



THE CONNECTIVE TISSUES. 



AEEOLAK AND ADIPOSE TISSUE. 



1. TAKE a little of the subcutaneous tissue or of the interniuscular connective 

 tissue of a rabbit or guinea-pig and spread it out with needles on a dry slide 

 into a large thin film. Keep the centre moist by occasionally breathing on 

 it, but allow the edges to dry to the slide. Before commencing put a drop 

 of salt solution on a cover-glass, and now invert this over the film. Ex- 

 amine with a high power. Sketch one or two bundles of white fibres and 

 also one or two elastic fibres, distinguishable from the former by their 

 sharp outline, isolated covirse, and by their branching. Sketch also one or 

 more connective-tissue corpuscles, if any such are visible in the clear inter- 

 spaces. Look also for migratory cells (lymph-corpuscles). Next carefully 

 remove the cover-glass and replace the salt solution by dilute acetic acid. 

 Watch its effect in swelling the white fibres and bringing more clearly into 

 view the elastic fibres and corpuscles. Look for constricted bundles of white 

 fibres. 



2. Make another film in the same way, but mount in dilute magenta 

 sohitioii l instead of saline solution. The elastic fibres are deeply stained by 

 the dye ; the cells are also well shown. When the staining is completed pass 

 dilute glycerine under the cover-glass and cement this at once with gold 

 size. 



8. Prepare another film of the subcutaneous tissue, including a little 

 adipose tissue. Mount in glycerine and water, coloured by magenta, with a 

 piece of hair under the cover-glass to keep this from pressing unduly upon the 

 fat-cells. Cement at once with gold size. Examine first with a low and after- 

 wards with a high power. The nucleus and envelope of the fat-cell are well 

 brought out by the magenta, and if from a young animal, fat-cells will be 

 found in process of formation. Measure and sketch two or three of the cells. 



4. Spread out another large film of connective tissue, letting its edges dry 

 to the slide. Place on its centre a large drop of nitrate of silver solution 

 (1 per cent.). After ten minutes wash this away with distilled water, mount 

 in Farrant l , and expose to the sunlight until stained brown. Sketch the out- 

 lines of two or three of the cell-spaces. 



The connective tissues include areolar tissue, adipose tissue, elastic 

 tissue, fibrous tissue, retiform and lymplioid tissue, cartilage and bone. 

 All these tissues agree in certain microscopical and chemical charac- 

 ters. They, for the most part, have a large amount of intercellular 

 substance in which fibres are developed, and these fibres are of two 



1 See Appendix. 



