1908] 



CROCKER AND KNIGHT— CARNATIONS 



265 



injury to the plant through the absorption of gas by the soil and later 

 by the roots. Also no definite determination of the toxic limit of the 

 gas can be made, for the amount absorbed by the soil is not determi- 

 nable. 



To avoid such sources of error the buds and flowers still intact 

 were exposed individually to the desired concentrations of the gases. 

 This was accomplished by the use of the apparatus shown in fig. 1. 



Fig. 1. — For description see text. 



The bottle a is furnished with a three-holed rubber stopper. In one 

 hole of the stopper is a straight glass tube reaching nearly to the 

 bottom of the bottle. A calcium chlorid tube (d) is attached to the 

 projecting end of this tube by means of a rubber tube furnished with 

 a pinchcock (e). In the second hole of the stopper is a short bent glass 

 tube (/) , the outer end of which is furnished with a rubber tube and 

 pinchcock (g) . The third hole in the stopper is small and is capable 

 of having the stem of the carnation inserted from the side by a split, 

 which reaches from the hole to the margin of the cork. In setting 



