154 



84.77 feet in height, waicli is believed be the highest prevssure of vege- 

 table sap ever before recorded. 



To determine, if possible, whether any other force than the vital 

 action of the roots was necessary to produce the extraordinary 

 phenomena described, a gauge was attached to the root of a black 

 birch-tree as follows: The tree stood in moist ground at the foot of 

 the south slope of a ravine, in such a situation that the earth around it 

 was shaded by the overhanging banks from the sun. A root was then 

 followed from the truuk to a distance of 10 feet, where it was carefully 

 cut off one foot below the surface, and a piece removed from between 

 the cut and the tree. The end of the root, thus entirely detached from 

 the tree, and lying in a horizontal position at the depth of one foot in 

 the cold, dam[) earth, unreached by the sunshine, and for the most part 

 unaffected by the temperature of the atmosphere, measured about one 

 inch in diameter. To this was carefully adjusted a mercurial gauge, 

 April 26. 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 unequaled 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 im])osed upon them by ingenious 

 I)hilosophers, such as osmose, exhalation, dilatation, contraction, 

 oscillation, capillarity, &c., was quite sufficient to account for the most 

 essential of the curious phenomena connected with the circulation of 

 sap. Unfortunately, in an attempt to ijicrease the capacity of the 

 gauge, the bask of the root was injured, and this most interesting- 

 experiment terminated. There can be little doubt that future trials, 

 carefully conducted, with suitable apparatus, will acliieve still more 

 marvelous results. 



The original experiment ui)on the grape-vine, the story of which has 

 come down to us through a hundred and tilty years, was repeated May 

 9, and a pressure of 49.52 feet of water obtained 3Iay 24. This is Gi 

 feet higher than was observed by Hales. 



The peculiar features of the pressure of the viije-sap are: Its late- 

 ness in the season; its a])parent 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 20 to July 20, when the observations ceased. 



In conclusion, we may as well admit that life is still a special force, 

 iind not to be resolved into any other sort or combination of attrac- 

 tions or repulsions, whether called electricity, osmose, or any other name. 



There is, obviously, need of much more investigation and definite 

 knowledge coucerr.ing the phenomena of vegetable nutrition and devel- 

 opment; and it may be well to remember that we are everywhere sur- 

 rounded by objects for scientific research, demanding our utmost talent, 

 patience, and skill, but sure to give ample and profitable results to 

 every diligent inquirer. We are often inclined to encourage ourselves 

 to remain in ignorance and idleness by dreaming of grand opportunities 

 for study in some far-olf time or place ; but let us all keep in mind the fact, 

 so familiar to every thoughtful student of nature, that within the lim- 

 ited circle of our vision lie concealed more mysteries than with our best 

 endeavors we can ever solve. 



PtOCKY Mountain Grasses. — The collection of grasses made in the 

 Rocky Mountains of Colorado, last year, by the botanists of Lieutenant 

 Wheeler's expedition is the largest and coaipletest, ])erhaps, ever obtained 

 in that region ; and although most of the species are well known to science, 



