444 PLANTAR SYSTEM. 



horny frog, taking a direction downward and forward, the same 

 as that in which the fibres of the horn grow. 



The vascular covering succeeds the cuticular, lying immediately 

 underneath it. It consists of a network of bloodvessels, princi- 

 pally veins, but which are not so thickly set as upon the sole. 



The JibrO'Cartilaginous case comes next. We find it spread 

 over those parts most subjected to pressure, and to be, in many 

 places, one-fourth of an inch in thickness. From its interior are 

 sent off numerous processes, pervading the elastic matter of the 

 frog, forming so many septa intercrossing one another, and di- 

 viding it without any notable regularity into many unequal com- 

 partments. In the posterior and bulbous parts, the septa exist in 

 greater numbers, and are closer arranged than in the middle parts. 

 The fibres of this vaginal substance run obliquely downward and 

 forward, and become intermixed around the borders with those 

 of the bars and sole. 



The elastic interstitial matter, however, composes the bulk of 

 the sensitive frog. It consists of a pale yellowish soft substance, 

 which has been mistaken for fat or oil, and hence has been named 

 *' the fatty frog." When cut deeply into, it exhibits a granulated 

 appearance, and the fibrous intersecting chords become apparent, 

 putting on the ramous arrangement of a shrub or tree. Altogether, 

 the sensitive frog forms a peculiar, spongy, elastic body, for which 

 we lack some more appropriate name. 



*»* The Bloodvessels and Nerves of the Foot will be found described 

 in their places, in the circulatory and nervous systems. 



