EXPLANATION OF THE PLATES. 



PLATE V. 



Fig. 1. Exhibits the circulation in a portion of the tongue of 

 the frog, the larger vessel is seen to be accompanied 

 by a nerve, as is usually the case, and in all the vessels 

 are shown the red and white blood corpuscles, with 

 their differences of form, size, structure, colour, and 

 position ; the general direction and appearance of 

 the muscular fibres, are likewise indicated. This 

 figure is magnified 350 diameters. 



2. Represents the distribution of the smallest capillaries 

 in the web of the foot of the frog, in which it is seen 

 that the blood corpuscles circulate only in single 

 series, the pigment cells, cellular tissue of the paren- 

 chyma, and the beautiful hexagonal and nucleated 

 tessellate epidermis are likewise exhibited. This 

 figure is magnified to the same extent as the last. 



