BLOOD. 3 ? 



What a striking spectacle is now presented to us, as 

 with a power of 300 diameters we gaze on the web of the 

 foot ! There is an area of clear colourless tissue filling 

 the held, marked all over with delicate angular lines, some-- 

 thing like scales ; this is the tesselated epithelium of the 

 surface. Our attention is caught by a number of black 

 spots, often taking fantastic forms, but generally some- 

 what star-like ; these are pigment cells, on which the 

 colour of the animal's skin is dej)endent. But the most 

 prominent feature is the blood. Wide rivers, with tor- 

 tuous course roll across the area, with many smaller 

 streams meandering among them ; some pursuing an inde- 

 pendent course below the larger, and others branchingout 

 of them, or joining them at different angles. The larger 

 rivers are of a deep orange-red hue, the smaller faintly 

 tinged with reddish-yellow. In some of these channels 

 the stream rolls with a majestic evenness ; in others it 

 shoots along with headlong impetuosity ; and in some it is 

 almost, or even quite, stagnant. By looking with a steady 

 gaze, we see that in all cases the stream is made up of a 

 multitude of thin reddish disks, of exactly the same dimen- 

 sions and appearance as those we saw just now in the 

 Frog's blood; only that here, being in motion, we see very 

 distinctly, as they are rolled over each other, that they are 

 disks, and not spherules ; for they forcibly remind us of 

 counters, such as are used for play, supposing they were 

 made out of pale red glass. 



It is charming to watch one of these streams: selecting 

 one of medium size, where the density is not too great to 

 see the individual disks, and, tixing our eye on the point 

 where a branch issues from one side of the channel, mark 

 the disks shoot by one after another, some pursuing the 

 main course, and others turning aside into the branch, 

 perhaps so small as to allow of only a single disk to pass 

 at once. 



The streams do not pursue the same uniform direction. 



