( 302 ) 



Now when the nutritious matter is protruded from the veflel 

 placed in Q, towards R, in order to form the tide of the tube Q R, 

 it meets the nutritive fubftance protruded from R towards Q, to 

 make alfo the fide R Q, and when this matter or fubftance, fo pro- 

 truded for the formation of two diftindl velfels, and one fide of a 

 tube, is formed in great abundance ; it is fo comprefled on all fides, 

 that in the cavities of the tubes, it grows into irregular membranes, 

 as is here fhewn in fig. 36, between C R Q. 



And this is alfo the cafe with the fuperfluous matter protruded 

 from the afcending blood-veflels (as I call them), in D, R, S, E, for 

 the formation of the fides of the tubes D R, R S, and S E, where 

 alfo, from the comprefled matter, the membrane placed between 

 D E S R is formed. 



This formation, namely, each fide of the large tubes, being 

 formed of two diftin6l afcending veflels, is neceflary, for otherwife, 

 the large tubes in Ruflies would not adhere firmly. But as the 

 fides of the large tubes are made fo compadl, that little or no aper- 

 ture can be difcovered in them, fo, on the contrary, the mem- 

 branes, which, as I have faid before, are accidentally formed in the 

 cavities of the tubes, are very irregular, and have in them many 

 apertures, and alfo broken parts, fome of which have a cavity in 

 them, and their irregular formation feems to me, to proceed from 

 fuch extra nouriflinient not being fufficient to form entire mem- 

 branes. 



But what feemed moft worthy of note in thefe membranes was, 

 that their external edge feemed a little thicker, and that, in fo thin 

 a fubftance as were thefe membranes, various ftreaks could be dif- 

 tinguilhed, which I confidered to be velfels. And indeed, I am 

 perfuaded, that however thin and tranfparent the membranes 

 might be, they were no otherwife formed than of veflels joined 

 together. 



