HARVEY AND THE CIRCULATION. 241 



or how the blood after it ceased to flow in arteries, 

 reached the venous radicles; and that Malpighi, by 

 the aid of the microscope, discovered the hair-like 

 channels of communication between the arteries and 

 veins. But in this some injustice is done the genius 

 and industry of the great discoverer. Is it probable 

 that an investigator like Harvey would leave the cir- 

 cuit unsolved when he understood all other parts of 

 the circulation ? In fact he speaks of the blood pass- 

 ing through the parenchyma of the lungs, kidneys, 

 spleen and liver. It is possible that he considered the 

 passage as through pores, yet his idea of pores may 

 have been that of capillary vessels. He speaks of 

 having used a magnifying glass to observe the mo- 

 tions of the heart in the transparent sea-slug, there- 

 fore, may he not have made observations upon the 

 capillaries with this magnifying instrument? It is 

 not reasonable to suppose the blood from arteries 

 percolated through the flesh as water finds it way 

 through bog, or any porous medium, though, of course, 

 it is possible. The discoverer's own language on the 

 subject is not satisfactory. 



Leeuwenhock, an advanced histologist, at about 

 the time of Harvey's death, was quite plain in his de- 

 scription of the passage of blood from arterioles to- 

 venous radicles. He says : 



" I used every means I could devise to see the complete cir- 

 culation of the blood namely, that one of the smallest of those 

 vessels which we call veins, arose from another which is called 

 an artery, and afterward conveyed its contents to a large vein ^ 

 but I found this to be impossible, for when I followed the course 

 of the artery until it became so small as only to admit one or two 

 globules to pass through it at a time, I then lost sight of it. How- 

 ever, I was at length more fortunate leaving the wing of a bat, 

 and observing the tail of a tadpole. Here a sight presented itself 



