48 



The glass arm is supported in a short glass tube that is held between 

 two hardened steel points, the points being adjustable through the arms 

 of a brass y. Close behind the steel points is a small fork ; this fork, with 

 the glass arm embraces the stem of the plant, the fork permitting an adjust- 

 ment for large or small stems. These pieces of mechanism are supported 

 by a long wooden beam, that has a beveling near the end supporting the 

 arm. This adjustment is to accommodate plants of varying height. 



At the long end of the glass arm, and supported by the beam, is a small 

 wooden platform that in turn supports the revolving spool. The axis of 

 the spool is extended at one end beyond its supports, and carries a grooved 

 pulley, which is connected with a similar grooved pulley attached to the 

 hour hand spindle of the clock by means of a small rubber band. The 

 friction between the rubber and the grooved pulleys, and the uniform 

 tension obtained, precludes slipping. 



The way the instrument is used is to place the stem of the plant be- 

 tween the fixed fork and short arm of the glass rod. The distance between 

 the point of contact of the plant and the pivot is ? \ r of the distance from 

 the blackened glass rod to the pivot, so that any growth of the plant is 

 magnified 40 times on the blackened rod. Thus a growth of r oVe of an inch 

 will be represented by fe of an inch on the blackened rod. 



One of the features of the blackened glass rod is that a permanent rec- 

 ord can be obtained by making a print of it on sensitized paper, from 

 which direct measurements can be made. 



A STATE BIOLOGICAL SI RVEY \ SUGGESTION FOR OUR SPRING MEETING By L. 



M. Underwood. 



The apical growth of the thallcs of pucus vesiculosus. By D. M. Mot- 

 tier. 



Symbiosis in orchidace.e. By M. B. Tiiom. 



