EAR OF THE MOUSE. 231 



Tf you do not mind snipping a papilla from your own 

 tongue with a sharp pair of curved scissors and soaking it 

 in a solution of soda for a few minutes, it becomes trans- 

 parent and the nerve-fibres are distinctly seen. In some 

 sections of the skin, hair-follicles are visible, and the 

 foot of the Cat exhibits these. In other preparations the 

 sweat-glands are shown, which are long tubes coiled into a 

 knot near the closed end, and a straight or spiral duct 

 piercing the skin at the surface between the papillse. These 

 glands are most numerous as well as large in the palm of the 

 hand there are 2736 in each superficial square inch ; 

 upwards of two millions in the whole body, carrying off car- 

 bonic acid and water as well as various other substances 

 superabundant in the system chloride of sodium, muriate 

 of ammonia, phosphate of soda, lactic acid, and carbonate of 

 lime. 



The lower animals, more particularly the naked Amphibia 

 as Frogs and Toads exhale carbonic acid gas most abundantly 

 by the skin, and respire also, absorbing water as well as air, 

 by means of the sudoriparous glands. 



THE SKIN OF THE TOAD 



is very interesting, for it shows not only the network of the 

 capillaries, but the pigment-cells beneath. 



CILIARY PROCESSES. 

 THE EYE OF THE OX. 



This is a magnificent object, exhibiting the blood-vessels 

 of the choroid membrane and ciliary processes. 



THE EAR OF A MOUSE. 



A really beautiful preparation, showing the cartilage-cells 

 and the structure of the mouse's hair, also the injected 

 arteries and veins. The cartilage-cells are simple in this 

 part of the body, resembling the parenchyma of vegetables, 

 and the substance is without blood-vessels, being nourished 



