210 THE AMERICAN MONTHLY [July, 



The lattel* is studied after picro-carmine staining. We 

 thus obtain either the vascular Layer or the non-vascular. 

 In the latter the elastic network of the mesentery is 

 observable. 



3. — The pericardium, the pleura, the peritoneum, the 

 synovial membranes are studied by transverse sections, 

 made after alcoholic hardenings. Stain by picro-car- 

 mine ; mount in glycerine with a little picro-carmine. 



CARTILAGINOUS TISSUE. 

 The study of this is very simple. We will first study 

 hyaline cartilage. A frog's xiphoid cartilage, the sclero- 

 tica, or the inferior angle of a salamander's or a triton's 

 scapula may be used ; in the last mentioned the cells are 

 colossal. . • . Mount in a drop of aqueous humor. . . . 

 Make sections from the fresh head of a frog's femur ; in 

 a drop of water can be seen the retraction of the proto- 

 plasm which gives each cell the stellate appearance 

 which many authors have believed to be normal. 



In fresh preparations the action of stains is easily 

 studied. It is best to use sections of cartilage fixed by 

 picric acid. A fragment is placed for 24 hours in a sat- 

 urated aqueous solution of the acid ; the sections are 

 soaked in water until the yellow color has disappeared. 

 Put some in alum carmine. After a few minutes, wash, 

 mount in water, for which glycerine should be substi- 

 tuted by allowing it to run under very slowly. The nu- 

 clei are stained lilac red. 



In this study Ranvier uses the purpurine extracted from 

 madder. To prepare this, boil 200 grms. of water and 

 1 grm. of alum ; when in ebulition add the madder and 

 and continue to heat. In ten minutes filter while hot 

 and add 60 c. c. of 36° alcohol. This should be used 

 fresh as it will keep for only a few weeks. The sections 

 are left in a few c. c. of the solution for 24 hours. Wash 

 in water ; mount in glycerine. The nuclei are stained 

 red, the basis substance rose. . . . 



