26 



Scientific Proceedings, Royal Dublin Society. 



brown. This change probably indicates the introduction into, or the pro- 

 duction in, the transmitted water of some clogging material; for, instead of 

 an increase in the amount transmitted downwards after the removal of the 

 supposed vital lifting forces, we see from the Table that the amount is 

 diminished. According as the downward stream washes out this clogging 

 material, the original rate of transmission is approximated to, but during the 

 experiment not attained. It is evident that if there was any considerable 

 length of branch below the steamed part, this material would accumulate 

 tliere. 



The appearance of this material in the water transmitted by a steamed 

 branch is of interest in connexion with some experiments discussed later. 



The small rise in the amount transmitted by the control branch noted 

 immediately after the observations were renewed is probably to be attributed 

 to a rise in temperature and consequent reduction of viscosity. 



12 9' TtKf ofjadttt. 



The effect of steaming on the experimental branch and the uniform 

 behaviour of the control is clearly brought out in fig. 2, in which the 

 ordinates are grammes of water transmitted per 10 minutes, and the abseissse 

 are the times of the observations. The full line connects the successive 

 observations on the control branch ; the dotted line joins the observations 

 on the experimental branch. The gap indicates the interval during which 

 the cistern was emptied, and steam was applied to the experimental 

 branch. 



Change taking place in the experimental branch demonstrated by the exit 

 of coloured liquid below after the application of the high temperature renders 

 the experiment somewhat unsatisfactory ; for, although the experiment gives 

 no indication that the removal of vital processes from the stem does away with 

 lifting forces opposing the downward motion of water, yet it is just con- 

 ceivable that, if these forces previously existed and were removed, the clogging 



