i:i26 ELEMENTARY BIOLOGY. [CHAP. 



/3. The cells ; irregular, flat, and close fitting. 



y. The cell structure and nucleus. 



S. Look for lymph stomata ; perforations of the 

 membrane, each surrounded by small more 

 deeply stained cells. 



Should the silver nitrate reaction fail, the 

 methylene blue process may be tried, as follows. 

 Place for 10-15 minutes in 4 per cent, solution 

 methylene blue. Transfer to saturated solution 

 of picrate of ammonia for half an hour ; wash in 

 the same and examine in weak glycerine. 

 d. Stratified epithelium ; see epidermis § 15. iii. 



3. Connective tissue. 



Of this there are two main varieties, a. and b. 



a. White fibrous tissue. This occurs typically in 

 tendons, but is mixed with the other tissues. 

 Tease out a bit of fresh tendon in water : examine 

 with a high power. 



a. It is chiefly made up of very fine wavy fibres 

 which, in the aggregate, impart a glistening 

 white colour to the tissue (white fibres); they 

 run in parallel bundles and do not branch. 



/?. Treat with dilute acetic acid. Most of the above 

 disappear, but a few well-defined curled fibres 

 (yellow elastic fibres) remain. Besides these 

 small irregular protoplasmic masses are brought 

 into view (connective-tissue corpuscles). 



b. Areolar tissue. Lay bare the muscles of the hind- 

 limb ; sheets of areolar tissue will be seen passing 

 between them and the integument. Remove one 

 of these, being careful to avoid undue stretching 

 and transfer to a slide : examine in water. 



