INSTINCT OF PLANTS. 215 



they come in contact with a fluid which first paralyzes them, 

 and then hastens their decay and absorption. 



Not less wonderful are the instinctive movements by which 

 climbing plants seek for, and attach themselves to, a support. 

 Twining vines, like the hop, the bean, and the morning-glory, 

 exhibit a revolving movement of their extremities, until they 

 come in contact with some object around which to coil. Each 

 species has its own peculiar direction, from which most of 

 them never vary. A few, like the hop, wind from the right 

 upward towards the left, moving like the hands of a watch, 

 but most, like the bean, move in an opposite direction. The 

 squash, however, is not a twining plant, but climbs by means 

 of tendrils. Nevertheless, the tip of a growing vine revolves 

 continually from left over to right, in evident search for a 

 support. 



Mr. J. J. H. Gregory informs us, that if a shingle be set 

 into the ground near the tip of a growing squash-vine, it will, 

 in a day or two, be seen turning towards it; and that, if the 

 shingle be removed to the opposite side, the direction of the 

 vine will again be changed. He also states that he has 

 observed a squash-vine, after running along on the ground ten 

 or twelve feet, and then passing under the branches of a tree 

 which were four feet above it, to stop and turn upward towards 

 the branches. After growing in this direction till it could no 

 longer sustain itself, the vine fell to the ground ; but instead 

 of proceeding horizontally, it again rose into the air, again to 

 fail. A third effort was made before the plant was willing to 

 give up and trail humbly on the earth. 



The end of the vine under observation was constantly 

 elevated to the sash-bars and glass above it, sometimes to the 

 height of two feet, and as it increased in length, was pushed 

 along against them. The extent and velocity of the terminal 

 motion were doubtless greatest in August, when growth was 

 most rapid. The record, however, was made in November. 

 The time occupied in each revolution was variable, and the 

 long diameter of the ellipse described, which was horizontal, 

 measured about two inches. 



The tendrils of the squash-vine were produced at the nodes, 

 and the main stalk was hollow and divided into several 

 branches at a point three or four inches distant from the vine. 



