82 



The collection numbered 510 species, distributed among 459 Phanero- 

 gams and 51 Pteridophytes. In this limited space no mention has been 

 made of species, the object being only to present the geiieral character of 

 the flora of the mountain, as shown by the distribution of certain families 

 and genera. A more complete report will be published later, with notes 

 on species. 



Ax APPAKATIS FOR DETERMINING THE PERIODICITY OF ROOT PRESSIRE. By 



M. B. Thomas. 



[acsthact.] 



The paper presented the need of a self-registering apparatus for deter- 

 mining the periodicity of root pressure, and gave an outline of the ones 

 now in use, all of which were seen to need constant attention. An appa- 

 ratus made in the following manner was suggested. The base of the in- 

 strument is about 1^x3'^ and is supported by legs about ?/^ high. About 

 W^ from one end and in the center of the base is erected a standard about 

 2^ high and 4'^ in width. On the short end of the base and near the post 

 is fastened a set of strong clock-works. The works are covered with a box 

 and the end of a cylinder (V in diameter and V 10^' high is fastened to the 

 hour pinion of the clock by means of a pin passing through a hole in the 

 end of the pinion and fitting in a slot in the end of the cylinder. The top 

 of the cylinder is held in place by a pin passing through a support from 

 the main pillar and a hole in the end of the cylinder. To the large upright 

 pillar is fastened a U tube of about V in diameter ; one arm being nearly 

 as high as the pillar and the other but half the height. The tube is filled 

 with mercury to within about an inch of the top of the short arm. The 

 stem of the plant is cut off near the base and placed in position. An in- 

 verted U tube is fastened lo the stem in the usual way by means of a rub- 

 ber tube fastened with wire while the other end of the U tube is connected 

 with the larger one in the same way. The small XJ tube is filled with wa- 

 ter through an opening in the top. The cylinder which is made of light 

 tin is blackened by revolving it slowly in the flames of a candle or gas jet. 

 The indicator consists of a light steel wire with a cork at the end some- 

 what smaller than the diameter of the tube. This rests on the mercury. 

 It is then at the top of the tube bent twice at right angles and allowed to 

 extend to the bottom of the cylinder where it is again bent twice at right 



