62 



OiR' pipe would be surticient for a small tal)le. .so tliat one luiglit tliMs utilize 

 a small corner of a room. Pipes driven into the ground are, of course, practica 

 ble only when the laboratory is on the ground Hoor and does not require too great 

 an extent of the pipe above the ground. 



The special features of these shelves are their cheapness, the carrying of a 

 number of shelves on the same pair of pipes, and the ease with which they can 

 be fixed up, so that one might readily tel up shelves for dif- 

 ferent pieces of apparatus. 



I use the shelves for work where a )>lant is on a lower 

 level than the apparatus used with it. This result is gotten 

 by boring a hole through the slielf and fastening the rod of 

 a ring-stand in the hole with a nut. The ring can then be 

 adjusted to any height on the rod. 



New Ai'i'ARATUS i--or Vegetahle Physiology. 

 By J. C. Arthir. 



[Ahstract.J 



The following apparatus was described : (1) A res})iration 

 apparatus to determine the amount of carbon dioxide exhaled 

 by breathing plants within a certain time at a fixed tempera- 

 ture, the baryta method being used; (2) a centrifugal appa- 

 ratus for revcdving growing plantlets at a high speed, to replace 

 gravity with a similar force, that may be varied at pleasure, 

 in order to determine its effect in giving direction to the 

 forming organs of plants; (:■$) a gas chamber to supply different 

 'gases to living tissues under the microscope; (4) a slide with 

 binding posts to convey a current of electricity through living 

 tissues under the microscope; and (5) a hygrometer to exhibit 

 the comparative rate of evaporation of water from the two 

 sides of a leaf. An instrument of each kind was exhibited, 

 except the first one mentioned, which was illustrated with a 

 drawing. 



1. Thk Resi'iration Api'ARATx's consists of a small glass 

 chamber in which the seeds or other growing parts are placed. 



This is suspended by means of a brass cover, in an outer 

 jar containing water of suitable temperature. The respiration 

 chamlier is connected through jiotash bull)s and a wash bottle 

 with an aspirator, so that to begin with, all carbon dioxide may 



