iN95J MICROSCOPICAL JOURNAL 265 



This pre})aration will demonstrate the layer of proto- 

 plasm clothing the surface of the glomerule. A rabbit's 

 kidney is injected with Prussian blue [the method will 

 be described hereafter), fixed by 2 per cent bichromate 

 (be sure to slit the kidney in many places after the in- 

 jection mass is cold, so that the fixative may penetrate 

 more readily), harden in gum and alcohol. Cut very 

 thin sections either parallel with the surface or with the 

 medulary radiations. Stain in picro- carmine (24 hours), 

 or by Magdala rose (a few drops of a saturated alcoholic 

 solution in a glass of water). Preparations injected with 

 blue, stained in Magdala rose are to be examined in 

 water ; the nuclei proper of the capillaries being drowned 

 by the blue mass, the nuclei of the cells enveloping the 

 glomerule are stained pure violet, the protoplasm of the 

 cells amaranth rose. 



To Inject the Blood Vessels. — When in- 

 jecting the sub-diaphragmatic part of a rat's body the 

 kidneys are often injected in a remarkable way. Re- 

 move one, slit it and put it in the ammonia bichromate. 

 In 8 or 10 days wash, harden in gum and alcohol, sec- 

 tion, stain in alum carmine, mount in balsam. It is well 

 to make transverse and longitudinal sections. 



To Inject the Uriniferous Tubules. — This is an ex- 

 ceedingly delicate operation, usually successful only af- 

 ter repeated trials. 



ChrzonczetDski' s Method. — This consists in injecting 

 into the animal's blood a coloring matter to be eliminated 

 by the kidneys (distilled water, 30 ; carmine, 3 ; ammo- 

 nia, 1.50). Forcibly immobilise a rabbit, lay bare the 

 jugular vein upon which place a ligature, and open the 

 peripheral end. Allow from 15 to 20 grms. of blood to 

 flow, tie the peripheral end and inject by the central 

 part 15 to 20 grs. of the carmine solution. In an hour 

 open the abdomen, tie the ureter, open the renal artery 

 and vein, and inject through tlie artery a solution of 



