14 THE CAUSES OP FLUCTUATIONS IN TURGESCENCE 



of 50c.c. In this case about 50c.c. had traversed the boiled portion of the petiole 

 within twenty-four hours, for the loss by mere evaporation in a check bottle of water 

 was almost inappreciable during the same period. The nine pairs* of pinna? which 

 had been left on the leaf remained quite green and turgid, 



Experiment F7JJ.— Two leaves of Cassia alaia were taken, and all the pinnae save 

 the two terminal pairs were cut off. One specimen was then entirely immersed in 

 boiling water for a minute, and the lower part of the petiole of the other was similarly 

 treated. The extremities of the petioles were then freshly divided under water and 

 set side by side in marked water-bottles. On the following day the water in the bottle 

 containing the wholly boiled specimen showed a loss of Kte.e., and that in the other 

 one of llc.c. The pinnae in the wholly boiled leaf were quite flaccid, drooping, and 

 brownish, whilst those in the other were fully expanded, green, and turgid. Twenty- 

 four hours later an additional loss of 7c. c. was registered in the former and one 

 of 8c. c. in the latter specimen. The amount of water absorbed by the wholly dead 

 leaf during the entire course of the experiment was only 5c.c. less than that in the 

 case in which the lower part of the petiole alone had been boiled ; but in estimating 

 the amount of absorption due to the vital activities of the tissues in the latter it must 

 be borne in mind that the amount of loss due to simple evaporation in it was certainly 

 much less than in the other specimen, in which the retentive power for fluid connected 

 with functional activity had been totally abolished. 



Experiment IX, — Two leaves of Cassia alata, each bearing eight pairs of pinnae 

 after the removal of the basal pair, were set side by side in marked water-bottles, the 

 lower part of the petiole having in one case been boiled for two minutes and in the 

 other left intact. Twenty -four hours later the pinnae of both leaves alike were fully 

 expanded, green and turgid, and the loss of water registered by each bottle was 2Sc.c. 

 The boiled portion of the petiole o£ the one leaf was quite brown and the cortical 

 parenchyma flaccid. One phenomenon which presented itself in this case was that 

 the absorption of water was primarily more rapid in the specimen in which tin? lower 

 part of the petiole had been boiled than in that in which it had been loft intact, this 

 no doubt being due to the aspiratory action of the gaseous contents of the water- 

 conducting system on contracting under the influence the fall of temperature subsequent 

 to removal from the boiling water. 



It appears clear from the previous experiments that the action of heat and 

 chloroform on living vegetable tissues is strictly localised to the parts directly exposed 



to their influence, and that, even where the exposure results in death, there is no 



propagation of any effects to protected parts, however close to and continuous with 

 the injured ones they may be. In other words, there is no evidence that the death 

 of the protoplasts in one part produces any appreciable direct results on the well- 

 being of neighbouring but protected parts. The quantity and quality of the water- 

 supply conducted by the vascular tissues remains inappreciably affected by chloroform ; 

 and although heat may temporarily affect the former, due to the expansion of the 

 gaseous contents of the conducting system which it induces, the obstruction thus arising 

 is transitory, and this being so, in neither case does the mere loss of tumescence 

 and death of neighbouring paits ordinarily give rise to any appreciable effects. Very 

 different results ensue, as is shown by the next experiment, where the reajrent which 





