3i EVENINGS AT THE MICROSCOPE. 



generally somewhat star-like : these are pigment cells, on 

 which the color of the animal's skin is dependent. But 

 the most prominent feature is the blood. Wide rivers, 

 with tortuous course, roll across the area, with many 

 smaller streams meandering among them ; some pursu- 

 ing an independent course below the larger, and others 

 branching out 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 look- 

 ing 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 dimensions 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 a7'e 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, select- 

 mg one of medium size, where the density is not too 

 great to see the individual disks, and fixing 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 their main course, and others turning 

 aside into the branch, perhaps so small as to allow of 

 only a single disk to pass at once. 



Tlie streams do not pursue the same uniform direc- 

 tion. The larger ones do indeed ; and their course is 

 from the exti*emity of the toes towards the body : these 

 are the veins ; but the smaller streamlets flow in anv 



