300 



LIGHT, HEAT, 



Sect. XIII. i. 4 



tanned into green by the fun's light, than etiolated animal bod 



become tanned ycWov/ by the fame means. 



Ladly. This retention of the hydrogen on the fkins of 

 and animals, when their perfpirable matter is d 



t) 



O 



light. 



d by which the for 



o 



pofed by the fun*s 

 id the latter yel- 



low, is evidently owing to the po 



f life ; becaufe when eith 



f them are dead 



dion of the funfh 



he water fprinkled 



them again blanches them, or bleaches them white. 

 It is hence evident, that the curious difcovery of Dr, Prieniey 



his green vegetable matter, and 



o 



o 



hen the fun fhone upon th 



quatic plants, gave out vital 

 lid the leaves of other plants 



did the fame 



mmerfed 



as 



obferved by Mr. Ingen- 

 houz, refer to the perfpiration of vegetables, not to their refpiration^. 

 Becaufe Dr. Prieilley obferved the pure air to come from both fides 



of the leaves, and 



from the ftalks of a water-flag, wh 



o 



th 



fide of the leaf only ferves the office of lungs, and certainly not 

 flalks. Exper. on Air, Vol. III. And thus in refped: to the circum- 

 flance, in which plants and animals feemed the farthefl: removed from 



h other. I 



their fuppofed mode of refp 



by which 



was believed to purify the air, which the other had injured, they 



eem to differ only 



degree; and th 



o 



y bet 



hem 



re 



brok 



4. Th 



fl: for light, as well as for 



air, which is fo vifible 11 



Botanic Garden, Vol. II 

 fcuta, (hews the former to be of great confequence to theii 



the growth of vegetables, as defcribed 



ftence as well as th 



Thus many fl 



follow the fun 



during the courfe of the day by the nutation of the ftalks, not by 

 the rotation of them, as obferved in the fun-fiower by Dr. Hales j 

 and the leaves of all plants endeavour to turn their upper furface to 



the light, which is their refpiratory organ, or lun 

 Sea. IV. 



fli 



Th 



