342 Curtis : The Work Performed in 



H 2 CeHjjOn H 2 NaCl H a O CeH^O^ H 2 ZnCl 2 



Taxus 33 48 53 50 Acalypha 50 52 62 59 



33 54 54 50 51 54 63 58 



33 5 8 56 51 5 1 6l 62 58 



34 61 60 51 52 62 62 62 



33 73 61 50 52 63 63 62 



33 74 62 51 



The few examples here given are typical of the variations re- 

 sulting upon a change of solution. The results seem to indicate 

 that in the case of NaCl and ZnCl 2 there is not apparent any spe- 

 cific relationship between the wall and any of the substances different 

 from that existing between the wall and water. Investigations upon 

 this point have not been completed. The accelerating effect follow- 

 ing the substitution of salt solutions for water appears to be due 

 to the osmotic action of the two fluids thus brought together acting 

 through the walls of the living cells. The fact that the rate often 

 accelerated for some time but finally declined would indicate this 

 relation. It is not probable that the dead cells play any role in 

 the acceleration of the rate. The measurements with sugar, how- 

 ever, indicate that the molecules are not freely transmitted and so 

 act as an effectual block to any osmotic action while the introduc- 

 tion of another solution would tend to remove the obstruction and 

 allow a renewal of osmotic action in the cells. This result would 

 appear to throw considerable light upon the manner of transmis- 

 sion of sugars through the stem and account for their meager oc- 

 currence in the sap. 



Solutions of 50 per cent, alcohol had a very marked effect upon 

 the conductivity of the cells, causing a marked and rapid decline 

 which was not changed with the introduction of water. Thus with 

 a rate of 46, 46, 47, 47, 47 under water pressure, with alcohol the 

 readings were 60, 61, 6^, 63, 64, followed with water 82, 83, 84, 

 85, 85. The results are evidently due to a molecular change in the 

 walls whereby their power of transmission has been materially in- 

 terfered with. The feeble attraction between the alcohol and the 

 molecules of the cell wall would tend to prevent imbibition and 

 doubtless leaves them less attractive to water. 



Temperature and Resistance 



For the purpose of comparison with effects upon capillary 

 tubes, observations were made upon the action of temperatures on 



