190 BOARD OF AGRICULTURE. 



the temperature of the atmosphere, measured about one inch 

 in diameter. To this was carefully adjusted a mercurial 

 gauge, April 26th. The pressure at once became evident and 

 rose constantly with very slight fluctuations until at noon on 

 the 30th of April it had attained the unequalled height of 

 85.80 feet of water. This wonderful result showed that the 

 absorbing power of living birch rootlets, without the aid of 

 any of the numerous helps imposed upon them by ingenious 

 philosophers, such as osmose, exhalation, dilatation, contrac- 

 tion, oscillation, capillarity, &c., &c., was quite sufficient to 

 account for the most essential of the curious phenomena con- 

 nected with the circulation of sap. Unfortunately, in an 

 attempt to increase the capacity of the gauge, the bark of the 

 root was injured, and this most interesting experiment termi- 

 nated. There can be little doubt that future trials, carefully 

 conducted, with suitable apparatus, will achieve still more 

 marvellous results. 



The original experiment upon the grape-vine, the story of 

 which has come down to us through a hundred and fifty years, 

 was repeated May 9th, and a pressure of 49.52 feet of water 

 obtained May 24th. This is six and a half feet higher than 

 was observed by Hales. 



The peculiar features of the pressure of the vine sap 

 are : its lateness in the season ;. its apparent independence of 

 the weather ; its uniform and moderate rise day and night to 

 its maximum ; its very gradual decline to zero, without any 

 marked oscillations ; and its constant and almost unvarying 

 suction of 4.5 to 6.5 feet of water, manifested from June 20th 

 to July 20th, when the observations ceased.* 



In conclusion, we may as well admit that life is still a spe- 

 cial force and not to be resolved into any other sort or combi- 

 nation of attractions or repulsions, whether called electricity, 

 osmose or any other name. There is obviously need of 

 much more iuvestio;ation and definite knowledo^e concernino: 

 the phenomena of vegetable nutrition and development and it 



* Prof. A. N. Prentiss, of Cornell University, states that he has found in Brazil cer- 

 tain trees which, during the dry season, when transpiration from the foliage is veiy 

 great, would suck air into a wound made in the trunk by the stroke of an axe so 

 forcibly as to cause a sound, amounting almost to a groan. 



