iv] of Glands and Tissues. 97 



"of the walls. But an objection to this view was afforded 

 " by the movement of the blood being tortuous and scattered 

 " in different directions and by its being united again in a 

 "determinate part. My doubt was changed into certainty by 

 " the dried lung of the frog which to a very marked extent had 

 " preserved the redness of the blood in very minute tracts (which 

 " were afterwards found to be vessels) where by the help of our 

 " more perfect glass there met the eye no longer scattered points 

 " resembling the skin which is called Sagrino, but vessels joined 

 "together in a ring-like fashion. And such is the wandering 

 " about of these vessels, as they proceed on this side from the 

 " vein and on the other side from the artery that the vessels no 

 " longer maintain a • straight direction, but there appears a 

 "network made up of the continuations of the two vessels. 

 " This network not only occupies the whole area but extends 

 " to the walls, and is attached to the outgoing vessel, as I could 

 "more abundantly and yet with greater difficulty see in the 

 " oblong lung of the tortoise, which is equally membranous and 

 " transparent. Hence it was clear to the senses that the blood 

 " flowed away along tortuous vessels and was not poured into 

 " spaces, but was always contained within tubules, and that its 

 "dispersion is due to the multiple winding of the vessels. 

 " Nor is it a new thing in Nature to join to each other the 

 "terminal mouths of vessels, since the same obtains in the 

 " intestines and other parts ; and, indeed, what seems more 

 "wonderful, she joins together by a conspicuous anastomosis 

 " the upper and lower terminations of veins as the most learned 

 " Falloppius has very well observed. 



" In order, however, that you may more easily grasp what 

 "I have just stated, and follow it with your own eyes, ligature 

 " with a thread at the spot where it joins the heart, the pro- 

 " truded and turgid lung of a frog whose body has been laid 

 "open, doing this while a copious supply of blood is flowing 

 " through the whole of it. 



" This even when dried will preserve its vessels turgid with 



" blood. And this you will see exceedingly well if you examine 



" it with a microscope of a single lens against the horizontal 



" sun. Or you may adopt another method of seeing these things. 



p. l. 7 



