▼OL. X.] PHILOSOPHICAL TRANSACTIONS'. 251 



not ; but when the air came to act upon them, the parts of the plant that had 

 suffered so much were soon corrupted by it. 



This being done, the experiment was next made the contrary way, that is, 

 with the leaves in the air, and the roots in a bottle of water that was in vacuo ; 

 and immediately air- bubbles were observed issuing out at the end of the roots in 

 vacuo. After this, putting water upon the leaves, to see whether this air came 

 from thence, these bubbles began to cease; and having taken away the water 

 wherein the leaves were, the bubbles began again to issue out at the roots as 

 before, and so continued for 24 hours after, but in a small quantity, till at length 

 they quite ceased. During these 24 hours the roots lengthened about 4 lines or 

 one third of an inch ; which is a little less than they usually do in the air. — ^The 

 plant was kept in this condition for 4 days on the engine, observing from time 

 to time to draw out the air that entered by the leaves ; then it began to wither, 

 and the roots shot no more. 



Another time, putting two twigs of balm, into separate phials full of water; 

 in 5 days they both shot roots. Including in the vacuum the one which had the 

 longest roots, without taking it out of its phial : at the end of three days, ob- 

 serving that it was withered in vacuo, it was taken out, and the phials were 

 changed, to see whether that which had remained in the air, and throve very 

 well in common water, would also thrive in water freed of air ; and whether 

 that which was withered in vacuo, would revive in the common water, and in 

 air. Four days after, the twig that had been in vacuo was quite spoiled, and 

 the other still verdant, but not thriving; and it was observed that it did not 

 begin to shoot in the water freed of air till ten days after it had been put in. 



This experiment drew another after it, viz. to know whether water purged of 

 air, was less fit than common water, to make plants vegetate. For this end 

 two phials were filled, the one with water purged, the other with common 

 water, and having put a twig of balm in each, both were left in the air. The 

 twig in the common water shot at the end of 6 days, and the other in 10 days 

 after it had been put in. 



Having repeated this experiment once more; the twig in the water freed of 

 air, began this time to shoot the 3d day, and the other in the common water, 

 again the 6th day. But it was remarkable, that the twig in the water purged 

 shot only one root, which grew very long ; and on the gth day only it began a 

 little to shoot another, which lengthened but one line in 2 days ; whereas the 

 twig in the common water had then Q or 10 roots, and all very long, having 

 lengthened 5 lines or more in a day. — ^Although this experiment appeared at 

 first contrary to the preceding, yet it still confirmed the first opinion^ that the 

 air which is mixed in common water serves for vegetation. 



KK 3 



