40 PHENOMENA OF PLANT-LIFE. 



black pig, a white pig and a lamb. The specific life of each, 

 and not its food, determines its form, size and character. 



To show still more impressively the peculiar powers of the 

 wood and bark to conduct the crude and elaborated saps in 

 either direction, and to act either as roots or branches, as 

 circumstances require, we will describe an experiment per- 

 formed by a French gardener, M. Carillet, at Vineennes, in 

 1866 and 1867. He selected two dwarf pear trees, grafted 

 on quince roots, which were from four to five feet high. One 

 of them was carefully dug up in April, 1866, and fastened in 

 an inverted position above the other. The leading shoots of 

 the two trees were now flattened on one side with a knife, 

 and the two surfaces firmly bound together in the usual 

 manner of splice grafting. The two shoots grew together, 

 and, in the course of the summer following, a few leaves 

 appeared on the main stem of the inverted pear tree, and also 

 on the main branches of the quince roots, which were entirely 

 in the air some eight or ten feet from the ground. The next 

 spring, scions from four varieties of pear were set upon the 

 four main branches of the quince roots, two of which lived 

 and grew several inches. Meanwhile, the inverted pear tree 

 bore two pears. Here, then, was a composite tree, con- 

 sisting, first, of a root of quince, then a pear tree, upon 

 this an inverted pear tree, which had branches consisting of 

 inverted quince roots, and these were surmounted by pear- 

 shoots of two unlike kinds. Upon such a specimen it would 

 be very difficult to comprehend the working of the imaginary 

 syphons of Dr. Pettigrew, already described. 



In order to illustrate the fact that the return of the elab- 

 orated sap was not the result of the force of gravity, a pend- 

 ant branch of weeping- willow was girdled last June. The 

 enlargement was on the lower side of the girdled place, show- 

 ing that the flow of the material formed in the leaves was 

 constantly towards the roots. (Fig. 36.) 



To learn whether sap would flow from the bark on the 

 upper side of a girdled place, a stem of white willow, an inch 

 in diameter and ten feet high, was selected, and a ring of 

 bark, one inch long, removed. The girdled place was then 

 wrapped in oiled paper, so as effectually to exclude the air 

 and the light. On the fifteenth of October, one month after 



