5^ 



PULMONARY ARTERIES 



Sect. IV. 4 



•3- 



evolved, like the brades themfelves with the corol and fexual organs, 

 by the fap-juice, forced up in the umbihcal veiTels from feme previ- 

 oufly prepared refervoir, without the neceffity of any expofition to 

 the air in leaves or lungs, which are not yet formed, though it may 

 acquire oxygenation in the fine arteries of the embryon buds, which 



are fuppofed to furround the horizontal air-veflbls obferved in the 

 bark of trees. 



I 



As foon as the feeds become impregnated, the corol and ne£laries 



■with the 

 feeds are 



fexual organs fall off, and the pericarp and its contained 

 then nourifhed by the blood, which is aerated or oxygen- 



ated in the bra£t 



floral 



Thus the flower of thecolch 



cum appears in autumn without any green leaves, and the pericarp 

 with its impregnated feeds rifes out of the ground in the enfuing 

 fpring on a ftem furrounded with bra^tes, and with other green leaves 

 below them, which produce new bulbs in their bofoms. ' 



The blood, which thus fupplies nutriment to the pericarp and its 

 included feeds, does not feem to require fo much oxygenation as that 

 which fupplies nutriment to the embryon buds ; whence the floral 

 leaves are in general much lefs than the root-leaves in many plants, 

 and than the common green leaves of almoft all vegetables. And in 

 the plant mentioned in No. I. 3. of this feflion, under the name of 

 fenecio bicolor, the under furfaces of the flem-leaves near the ex- 

 peded flower ceafed to be red like thofc of the radical leaves, which 

 feemed to (hew that the vegetable blood was in them lefs oxygenated. 



Whence it may be believed that lefs irritability may be necelTary 



for the growth of the feed than of the embryon bud, as the former 



And 



and 

 the 



V, 



^ 



*•> - 







does not yet perhaps poflefs fo much vegetable life as the latter, 

 laftly, that as the anthers and ftigma require greater irritability, 

 fome fen Ability, it was neceflary a fecond time to oxygenate 

 blood which fupplies them with nutriment in the corols of the flowers. 

 See Se6l. VII. 2. 4. 



3. Recapitulation of the arguments tending to Ihew that the leaves 



of 



