316 THE AMERICAN MONTHLY [Oct., 



water for 5 or 6 hours to harden the gelatine, remove 

 the organs to the bichromate solution. 



It is not impossible, but difficult, to inject a rat through 

 the carotid or the femoral arteries. . . . With strong 

 scissors cut the rat completely in two transversely through 

 the middle of the thorax. When the blood has ceased to 

 flow, put the lower half of the animal in a basin of warm 

 water and introduce the canula into the aorta until its 

 point has passed into the sub-diaphragmatic portion. Tie 

 in place, and inject. When the mass returns through 

 the inferior vena cava stop it by forceps, and continue 

 the injection to the point of resistance. This method 

 produces a fine injection of all the sub-diaphragmatic 

 parts of the body. . . . 



LYMPHATIC GLANDS. 



It is necessary to make a certain number of prepara- 

 tions to demonstrate the structure of the lymphatic 

 glands. 



1. — Remove a gland from man or from a dog, and put 

 it in the i alcohol. It is best to select a small gland, or 

 to divide it into several pieces if one has at his disposal 

 only a large specimen. In 24 hours wash in water for 

 20 minutes, treat with alcohol and with gum [as so often 

 described], and section. Put the sections in water for 

 i an hour to remove the gum. Select a section, not too 

 thin, and let it spread itself out at the bottom of a ves- 

 sel of filtered water. With a marten's hair brush strike 

 the entire surface without rubbing it. . . . Then turn it 

 over and repeat the operation on the other surface. The 

 purpose is to expell the lymphatic cells that infitrate the 

 gland, also the endothelial cells from the meshes of the 

 reticulated tissue. A method by which to obtain a more 

 rapid result is to put the section in a bottle half full of 

 water and to shake it violently. The lymphatic cells are 

 thus freed from the reticulum without the use of the 



