Jan. 1896.] BOTANICAL SOCIETY OF EDINBURGH. 



495 



111 Fig. 1, A represents the small tlask of about 100 c.c. 

 capacity. B is the entrance tube for the air supply, it 

 is connected with an apparatus for removing carbonic an- 

 hydride from the air. is a small U tube containing 

 little glass beads and a few drops of water. The air in 

 passing through this becomes exactly saturated with water 

 vapour at 57° F., and in this state it cannot take any 

 moisture from the germinating corn, neither can the corn 

 extract any moisture from the air supplied to it. Under 

 these conditions the quantity of moisture given to the 

 barley during steeping is kept constant throughout the 

 experiment. D is the exit tube for the air. It is furnished 

 at E with a small side tube or trap which is intended to 



intercept any condensed 

 moisture from the upper 

 cold part of the tube and 

 prevent it getting into the 

 tlask. The upper extremity 

 of the tube F is connected 

 with a tube and bulbs con- 

 taining strong sulphuric acid 

 for drying the air as it comes 

 from the flask, and the dried 

 air is then passed through 



Ficr. 1. 



potash bulbs, etc., which remove the carbonic anhydride 

 coming from the barley. The carbonic anhydride absorp- 

 tion apparatus was weighed once a day to ascertain the 

 quantity of the gas absorbed. Air was drawn through the 

 apparatus very slowly and continuously from start to 

 finish of an experiment, except just at the times when 

 the weighings were performed, by a carefully designed 

 aspirator in which the speed of the air current could be 

 easily regulated. All parts of the apparatus were made as 

 small as possible on account of the small quantity of barley 

 operated upon, and the slowness of the aspiration. In 

 order to save time four pieces of apparatus, identical in 

 detail, were fitted up, the four flasks being all immersed in 

 the same large vessel, which enabled me to conduct four 

 experiments at the same time. 



The germination of the barley was carried on in this 

 apparatus, usually from 12 to 16 days. At the end of 



