1897 ] CURRENT LITERATURE 143 
highly irritable as tendrils, though they approach the less sensitive forms in 
sensitiveness. Petioles of Tropzolum encircled a support in five hours, Lopho- 
spermum in eleven hours, Clematis and Solanum in fourteen hours. The 
contact curvatures are often opposed by the heliotropic reaction of the leaf. 
Under such conditions a petiole of Lophospermum consumed forty hours in 
encircling a su 
The cpihedanatl upper side of the petioles of Solanum, Lankans 
mum, and Tropzolum, and the lower side of Clematis showed the greatest 
degree of irritability. 
In his comparisons the author assumes a latent period of AR to thirty 
minutes for tendrils, which in reality react in ten to fifteen secon 
The limited transmission of impulses in tendrils is duplicated a petioles. 
Curvatures, according to the author’s measurements, are due to an accelerat 
growth of the convex side. The portion of the petiole in contact with a 
support undergoes great increase in thickness, and if the mechanical system 
is in the form of a crescent or open ring, it is closed. 
Stretching tension exerts an influence upon twining petioles similar to 
that of typical organs. Stretching tension acting upon the encircling part of 
the petiole in some instances induced in some species an exaggeration of the 
contact effect, and in others a diminution. 
This paper has but recently reached the hands of the reviewer, and bears 
no date of imprint. Reference is made to a work published in 1892, and the 
reader has no means of determining the time of publication within five 
years.—D. T. MacDouGAL. 
