( 14 ) 



obferved, whicli la ft difcovcrcd vefiels were exceeding fmall in com- 

 j)arilbn of the former ; fo faiall, indeed, that if a large grain of fand 

 were divided into ten millions of parts, thefe veflii'ls would flill be 

 impervious to them. Hereupon 1 concluded that all the perpendi- 

 cular veOels which I had before difcovered in this wood, and through 

 wliich I had fuppofed the juices for the nourifhmet of the tree, and 

 its fruit, were conveyed, were really only air vellels ; for thofe 

 v.hich I now name air vedels are furrounded with three or four of 

 the very fmall vellels before mentioned. And I am clearly of opi- 

 nion, that thefe minute vefiels do conftitute and form thole others 

 which I name air vefiels, and conne6l them one with another ; and 

 that thefe fmaller vefiels convey all the nutritive fubfi;ance for the 

 fupport of the tree, its leaves and fruit, and that therefore they may 

 properly be named arterial vefiels. 



The wood which in jig. 8, is reprefented f})lit longitudinally, I 

 now cut or divided tranlVerfely, to fliew the nature of thefe vefiels 

 when infpe^led into or looked down upon, if I may fo exjn-efs my- 

 lelf; and sit Jig. ii, UVWYZ, a portion of it is reprefented as feen 

 by the microfcope, the natural fize of which was no more than 

 could be covered by a middling fized grain of l\md ; and in this 

 figure, between the vefiels compofing the wood, or the air vefiels 

 before mentioned, are feen the very minute vefiels which I call the 

 arteries of the wood cut tranfverfely ; but as they are fo very mi- 

 nute, I caufed four of the air vefiels to be drawn I'eparate as viewed 

 by a ftill deeper magnifier, that thefe laft might be the better dif- 

 tinguifiied, and thefe are fliewn at fg. ly, as they he between the 

 air vefiels. 



The dark ftreaks which are reprefented mfg. 1 1 , at W Y Z, are 

 a fmall part of the horizontal vefiels divided longitudinally, and 

 which vefiels are reprefented in/^.8, between G H, and I K. 



To this defcription I muft add a little piece of the fame wood which 



