X] CONNECTIVE TISSUE 79 



Tendon. A good preparation of the elastic fibres in tendon 

 may be made by placing a fresh rat's tail tendon in picric acid 

 and in water each for a day, and then staining with orcein. 

 Accompanying nearly every row of tendon cells will be seen one, 

 and sometimes two, fine elastic fibres ; here and there an elastic 

 fibre runs across, or sends a branch across to join a neighbouring 

 fibre. In the sheath of the tendon bundle are more numerous 

 elastic fibres, the sheath will be for the most part burst open, 

 but here and there the elastic fibres in it constrict the tendon 

 bundle. 



The cells may be stained by placing a swollen bundle in very 

 dilute hoematoxylin for a day ; it should be washed well with 

 water and mounted in glycerine. 



Sub-cutaneous tissue. The elastic fibres may be stained with 

 orcein in the manner given in 2, either in a dry film, or in a 

 moist film fixed with alcohol. They appear as small threads of 

 different size, here and there anastomosing. In the frog the 

 areolar tissue which, at the sides of the body, separates the 

 dorsal from the ventral lymph sacs has comparatively little 

 elastic tissue ; that stretching from the skin to the upper 

 ventral portion of the thigh has much. 



The basophil cells vary in appearance in different animals. 

 They are easily preserved and they stain with hsBmatoxylin, 

 safiranin and a number of reagents as well as with methylene 

 blue. 



Coarsely granular oxyphil leucocytes are often numerous, 

 they are perhaps best seen in dried films. 



The cells of connective tissue are fairly well seen in a film 

 fixed in 1 p.c. osmic acid for half-an-hour, overstained with 

 methylene blue, excess of stain removed with alcohol, and 

 mounted in balsam. 



Branched connective tissue cells are well seen in the tail of 

 the tadpole (Perenyi's fluid) stained with picrocarmine. The 

 surface epithelium is removed by brushing or partial teasing. 

 The preparation may also show a stage in the development of 

 capillaries. 



Fat tissue. The general characters may be observed in films 

 of sub-cutaneous fat, instead of in the omentum. 



