IX THE MOTOR ORGANS OF LEAVES. 



;3 



ammonia in the tissues, but that combinations must be formed within the cull-sap 

 which render it more or less permanently hygroscopic. The flower a did not undergo 

 complete collapse on removal from the ammonia chamber, but remained partially 



the open air. There can, therefore, bo no 



._ even alter prolonged exposure in 



tursrid 



after 



doubt that turgescence is mainly, if not solely, duo to the osmotic properties of the 

 cell-sap, and that losses in turgescence are due to diminished osmotic capacity in the 

 latter, and not to any increased filtrativo properties in the protoplasm. It is not, 

 however, quite clear that structural alterations in the protoplasm may not act in the 



of retarding losses in turgescence by pros* ntin 



(r 



an 



contrary direction, in the way 

 abnormal resistance to the elastic recoil of the cell-walls. When we consider the phe- 

 nomena presenting themselves in connection with death of tissues under the influence 

 of the vapour of osmic acid, there are many points suggesting that the abnormal 

 slowness with which loss of 

 is shown by the data furnished by the next two experiments. 



turgescence advances is due to such a causation. Thii 



Experimen t XXI V. 



A leaf of Kalanchos 



ing 8'38 grammes, was 



•loscd 



in a moist chamber containing a vessel of 2 per cent, solution of osmic acid. Visible blacken- 

 ing of the surface became apparent within the course of half an hour, but tho first 

 drop of exudation did not appear until two hours after exposure, and an hour later 



a certain 



following day 

 the texture re 



ber of scattered drop 



f black fluid had been excreted. < )n the 



leaf 



was 



black and bore numerous large inky drops of fluid, but 



ained quite firm and th 



lit was still 7*9 grammes. It was now 



placed 



in a 



simpl 



moist chamber, where it remained f«»r 



day 



fT< 



n.e 



successive losses in weight 

 are recorded below : 



cl 



1 



rred during the entire course of tho experiment 



Date* 



January 26th 



» 



» 



5> 



5? 



5* 



27th 

 28th 

 29th 

 30th 

 31st 



February 2nd 



5> 



>> 



>> 



5> 



*> 



yy 



3rd 

 4 th 

 5th 



6th 



8th 

 9th 



Weight 



• • ♦ 



. ■ • 



• • • 



■ • 



• • • 



• • • 



• • • 



• • • 



• • • 



• • • 



• • t 



8-38 

 7-90 

 7-78 

 7-64 

 7-57 

 7-49 

 7-30 

 7-20 

 705 

 G-91 

 6-84 

 660 



652 



Successive Total poroent- 



losses. 



• • • 



0-48 

 012 



014 



o-07 

 0-06 



010 



0-15 

 0-14 

 0-07 

 0-24 

 008 



age loss. 



5-7 

 71 



86 



96 



10-6 



12-8 

 140 



15-6 

 175 



183 

 21-2 

 221 



Here we have evidence of retarded loss in turgescence ; but the 



nued 



progress steadily, and there was no evidence of the absolute arrest of loss manifesting itself 

 in the case where death was caused by exposure to ammonia— vide experiment XIX. 

 The phenomenon appears rather to be the parallel of that presenting itself in cases 

 where the tissues are frozen, only that in this case the obstruction to the escape of 



volatile constituents and water from the tissues is a permanent one and does not, like 



that 



.blished by cold, disapv 



rem 



of the tissues from 



cond 



under 



Ann. Roy. Box. Gard. Calcutta Vol. VI. 



