mo 



Scientific Proceedimfs, Royal Dublin Society. 



\>y their passage out of the organs under pressure. Heuee it was to be 

 expected that the ratio of the electrolytes would remain sensibly the same 

 for the sap pressed from the living tissues and for that from tissues rendered 

 (permeable by liquid air. 



The results for the rhizome of Iris germanica and for the fruit of 

 'Citrus Limonum d,re exceptions, and may very probably be assigned to actual 

 differences in the sap from two apparently similar portions of the same massive 

 organ. It is also possible that part of this effect is due to the greater viscosity 

 of the sap from the treated organ. 



These two factors probably also accouut for the anomalous fall in conduc- 

 tivity noticed in the sap of the fruit Pyrus Mains and of Vitis vinifera 

 obtained by means of liquid air. 



It is certain tliat a much less extreme cold than that of liquid air would 

 render the protoplasm permeable (Maximo w, 16, 17, 18); but where liquid 

 air is available it has the advantage of being very rapid in its application, 

 and reduces the chances of change in the sap to a minimum. 



We have made a few experiments with the object of finding out if the 

 application of heat in a saturated atmosphere, or the exposure to ciiloroform 

 vapour, might be used as a substitute for exposure to liquid air. 



First, with regard to the application of heat, a quantity of leaves of 

 ■Ilex AquifoUum were divided down the midrib, and two samples, A and B, 

 were formed, each containing half of every leaf used. A was wrapped in moist 

 bibulous paper, enclosed in a metal box, and placed for ten minutes in a 

 water-oven at 95° 0. The half-leaves were then cooled on ice and pressed, 

 the sap flowing out easily. Sample B was immersed in liquid air, and theu 

 pressed, i The results of two pairs of comparative experiments were as 

 follows :-!—Nos. 500 and 501 were made on leaves of the antepenultimate 

 growths 5 while Nos. 502 and 503 were on leaves from the proantep enultimate 

 growths.! 



Ilex AquifoUum: leaves. 



■ From these results it is evident that ten minutes' exposure to 95° is not 

 sufficient to render tlie membranes permeable with certainty. ' Owing to the 

 likelihood of serious changes taking place in the sap, it would not be feasible 

 to exposie the. leaves for longer to so high a temperature. > 



