222 Objects for the Microscope. 



is thin, transparent and perfect, it will show the structure 

 and position of the nail, the corium and papillae beneath ; 

 the joints and shaft of each bone of the toe, with its attendant 

 arteries and returning veins ; also the hairs, with bulb and 

 follicle to each. In these hairs the outer cortical or invest- 

 ing membrane is distinctly seen, banded or crossed in the 

 centre with a double row of medullary cells. When these 

 last two slides have been looked at with a low power, 

 examine further with a half-inch. 



INJECTED PREPARATIONS. 

 THE KIDNEY. 



The Rabbit or the Cat gives an excellent preparation of 

 this organ. 



The whole substance of the kidney is made up of urinary 

 tubules, with attendant arteries and veins. These tubes or 

 passages are lined with cells like paving-stones, called 

 " epithelial cells," and those round bodies injected blue or 

 crimson are the Malpighian tufts, or -terminations of a 

 tubule, into which an artery runs and twists about, forming 

 a plexus of minute blood-vessels, ultimately uniting to a 

 single outgoing or efferent vessel, which branches off again 

 into a capillary network, situated in the cortical or outer 

 substance of the kidney. These solitary efferent vessels are 

 like the portal-vein system of the liver, both serving to 

 convey blood between two capillary systems. The inter- 

 stices between the blood-vessels, nerves, and tubules of the 

 kidney are occupied by areolar tissue. 



TONGUE. 

 Human Monkey Dog Cat Mouse. 



If a perpendicular section of the human tongue be 

 obtained, we shall see that it consists of a free surface, 

 covered with structures analogous to those of the skin, a 

 cutis or corium, on which are placed papillce, which are 

 more developed in the rough tongue of the Dog and the 

 Cat than in the human subject ; consequently an injection 

 of the dog's tongue is. a more beautiful object. The fungi- 



