Page:Researches on Irritability of Plants.djvu/40

Rh holding the glass recording-plate, moves up and down the top part of the upright. It is essential to have this slide so accurately fitted that the plate-carrier may be able to drop

smoothly and uniformly, without any jerking whatsoever. I have sometimes attained the same end by mounting the plate-carrier on wheels and letting it slide down vertical rails. The plate-carrier is allowed to drop by the running down of