224 * THE MICROSCOPIST. 



hours, or until the gum is hard enough. The sections 

 may be stained with carmine, logwood, silver, or gold. 



The following suggestions from Rutherford's Outlines 

 of Practical Histology, will be of service to the student in 

 this department : 



Most of the tissues required may be obtained from the 

 cat or guinea-pig. Feed the cat, and an hour or so after 

 place it in a bag ; drop chloroform over its nose until it is 

 insensible. Open the chest by a linear incision through 

 the sternum, and allow the animal to bleed to death from 

 a cut in the right ventricle. 



Divide the trachea below the cricoid cartilage and in- 

 ject it with J per cent, chromic acid fluid ; tie it to prevent 

 the escape of fluid, and place the distended lungs in the 

 same fluid, and cover them with cotton-wool. Change 

 the fluid at the end of eighteen hours. Allow them to 

 remain in this fluid for a mouth, then transfer to methy- 

 lated spirit till needed for mounting. 



Open by a linear incision the oesophagus, stomach, large 

 and small intestines, and wash them with salt solution (f 

 per cent.). Place a portion of small intestine in chromic 

 and bichromate fluid (1 gramme chromic acid and 2 

 grammes potassium bichromate in 1200 c.c. water) for two 

 weeks (change the fluid at the end of eighteen hours), and 

 then in methylated spirit till required. Act similarly 

 with parts of oesophagus, stomach and large intestine, in 

 J per cent, chromic acid for three or four weeks. A por- 

 tion of stomach may be placed in Muller's fluid till re- 

 quired for preparation of non-striped muscle, and of the 

 gastric follicles. 



The bladder may be treated as the small intestine. 



Divide one kidney longitudinally, and the other trans- 

 versely, and place in Muller's fluid. Change the fluid in 

 eighteen hours, and after four weeks transfer to methy- 

 lated spirits. They will be ready for use in two weeks 

 after. 



