Objects for the Microscope. 221 



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 papillae. These 

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

 the hand there are 2,736 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 

 by those which spread over them in the enveloping mem- 

 brane of the ear. 



They are the lowest order of animal cells, like the Algse 

 of the vegetable kingdom, without vessels of any kind, and 

 nourished by inhibition. 



THE TOE OF THE WHITE MOUSE. 



A very popular object, and worthily so. If the section 



