CHAPTER IV. 



ANIMALS AND PLANTS IN WHICH THE CIRCULATION 

 HAS BEEN OBSERVED UNDER THE MICROSCOPE.* 



"The most interesting active phenomenon -exhibited by 

 the Microscope is the circulation of the nutritious fluids in 

 animals and plants. In the former the corpuscles of 

 blood may be seen passing raj)idly along the capillary 

 ends of the arteries into those of the veins, when the 

 intervening membrane is sufficiently diaphanous, as in 

 the ear of the young mouse ; the fins and tail of the carp, 

 gold-fish, stickleback, tadpole, and of most small fish ; 

 and in the web between the toes of the frog, lizard, eft, 

 &c. For these purposes a magnifying power of from 100 

 to 200 diameters is sufficient. 



"In the Arachnida (Spider tribe), at the joint of the 

 legs I have observed the circulation very distinct, the 

 current of dark globules passing rapidly at each pulsation 

 of the dorsal vessel. In the antennae and wings of 

 terrestrial insects, it has also been seen when they have 

 just emerged from the chrysalis, as in the Perla viridis 

 and Semblis bilineata. In several aquatic larvae and 



* Extracted from Mr. Pritchard's List, p. 21. 



