Dixon — Changes in the Sap hy the Heating of Branches. 227 



In each case a sample of sap centrifuged from the fresh branch was tested ; 

 other similar tests were made upon that centrifuged from a branch immediately 

 after steaming, or centrifuged from a branch steamed a day or two previously, 

 or with the liquid centrifuged from a branch which had a day or two 

 previously been steamed and at once depleted of its sap by centrifuging, and 

 refilled with distilled water. These two last tests were made in order to see if 

 the poisonous materials are set free immediately into the sap on steaming, or 

 whether they are produced as subsequent degradation-products of the cells. 



In the table below, the sap obtained by centrifuging immediately after 

 steaming is termed " steamed direct " ; that which was centrifuged some days 

 after steaming is called " steamed indirect " ; while the liquid obtained from 

 the steamed branches which had been emptied of their sap, and subsequently 

 filled with water, is tabulated as " steamed indirect + water." Tlie ciphers iu 

 the table indicate that no effect was observable on that day of the experiment 

 under which the figure is placed, while a plus mark shows that an effect was 

 observed. Query marks indicate that only some of the leaves tested were 

 affected or that only slight protoplasmic contraction was observable. In each 

 case three or four leaves were immersed iu the liquid and used as tests. 



Table. 



' When the sap had stood in contact with the dead cells 

 the veins and blackening of some of the cells without marked 

 SOIENT. PEOC. R.D.S., VOL. XIV., NO. XV. 



for two or more days, discoloration of 

 contraction occurred on the fifth day. 

 2m 



