34 



THE CAUSES OF FLUCTUATIONS IN TUKGESCENCE 





which it originated. 



In cases of exposure to an atmosphere of ammonia there is no 

 evidence of any initial obstruction to the escape of fluid ; on the contrary, exudation mani- 

 fests itself with special rapidity, and it is only after some time that loss of turgescecne 

 ceases to occur and a condition of equilibrium is established between the osmotic capaci- 



* 



ties of the tissues and the elastic recoil of the cell- walls; but, when equilibrium has been 

 arrived at, it is stable. In the case of exposure to an atmosphere of osmic fumes, on the 

 other hand, we have from the outset very distinct evidence of the action of a factor 



Exudation appears excep- 

 tionally late and advances very slowly ; but, once established, it advances evenly and con- 

 tinuously, and there is no tendency to any establishment of a stable equilibrium until the 

 elastic recoil of the cell-walls has been fully satisfied. We have here evidence showing that 

 alterations in the protoplasm may retard the progress of the effects following loss in 

 osmotic property in the cell-sap, but none to show that any mere alterations in the 

 protoplasm will suffice* to give rise to loss in turgescence so long as the osmotic properties 

 of the cell-sap remain unaltered. 







obstructive to the normal loss in turgescence attending death. 





Experiment XXV. — A leaf of Kalanchoe, weighing 27-7 grammes, was set in an osmic 

 acid-chamber on the loth of March, the base of the petiole being immersed in water 

 and having been freshly divided subaqueously. On the following day it was entirely 

 blackened and had exuded numerous large drops of inky fluid along the margin of the 





lobes, but the weight, in place of being decreased 



htly increased, probably due 



to the addition of constituents from the osmic acid more than counterbalancing the 



weight 



oned by the exudation. It was now set in a simple moist chamber 



the petiole not being in water 



weights from the be 



It remained thus for the succeeding five day 



The 



5 



o 



of the 



sho 



below 



periment up to the close of this period 



ai 



Date. 



Weight 



March 15th 



16th 

 17th 

 18th 

 19th 

 20th 



>> 



» 



JJ 



» 



99 



• • • 



21st 



4 t « 



/ 



t • f 



• • • 



t • • 



♦ • * 



• • • 



• • • 



• • • 



• « • 



• # * 



• • • 



%*• 



• • « 



27-7 



27-72 



2713 



26-74 



26-30 



2505 



24*40 



+ 



002 

 0-59 

 0-39 



0-44 

 1-25 



065 



The percentage loss on total weight 



which the ammoniated leaf of 



during which it had been kept apart from water 



was now 11*9, or somewhat greater than that 

 periment XX had sustained at the close of the period 



was 



now once more set in water and subaqueously divided 

 for three more days, being daily weighed and anew set 



simple moist chamber. The petiole 



The leaf was kept thus 

 in water with a freshly 



ubaqueously exposed petiolar surface. Weighments for the period were as follows 



Date. 



Weight. 



March 22nd 



„ 23rd 

 „ 24th 



• • ' 



« • • 



« • • 



• ♦ • 



23-62 

 23-32 

 2309 



0-78 

 0-30 



0-23 









