28 THE CAUSES OP FLUCTUATIONS IN TUEGESCENCE 



above the great basal cell is apparently quite empty of all save fluid. At the same 

 time it is clearly related to continued protoplasmic activity, although this is not carried 

 on locally. This is shown very strikingly in cases where the mycelium and basal cells 

 are subjected to the influence of osmic acid. If a mass of the cowdung on which a 

 crop of fertile filaments in full turgescence is situated be moistened by a 2 per cent, 

 solution of osmic acid, and set under a dissecting microscope, a very beautiful and 

 interesting series of phenomena manifest themselves within the course of a minute or 

 two. Under normal circumstances, of course, the turgescence in the fertile filaments is 

 so excessive as to give rise to such a considerable excretion of fluid that they are 

 studded throughout by beads of it. Under the influence of the osmic acid these beads may 

 be seen rapidly to enlarge, and as they do so the filament gradually becomes flaccid and 

 collapses. The very fact that this rapid and complete collapse should attend the action 

 of osmic acid is in itself very strong evidence that the turgescence is independent of the 

 presence of any continuous stratum of protoplasm, seeing that the fixative property of 

 this re-agent for tissue elements seems to be due to its action in rendering the protoplasm 

 relatively impermeable ; and, when taken along with the histological evidence, it seems 

 conclusively to indicate that we are here dealing with turgescence due to extrinsic 

 agencies, due to the presence of materials which have not originated locally, but which, 

 having been developed in connection with the functional activity of the mycelium and 

 specially of the basal cells, have passed on into the interior of the fertile filaments. 

 Further, it is evident that these materials must be of unstable nature, so that turgescence 

 can only maintain itself against the factors making for filtration so long as a constant 



supply of them is being manufactured elsewhere and subsequently transferred to the 

 cavities of the filaments. 



Perhaps the most convincing proof of the indirect relation which turgescence bears 

 to protoplasmic functional properties, and of its direct dependence on osmotic peculiarities 

 in the cell-sap, is that which is afforded by the results of experiments in which, in the 

 course of killing the protoplasts of the tissues, we secure the artificial addition of osmotic 

 constituents to the sap. When we do so, we find in dealing with succulent tissues, such 

 as those of Kalanchoe, in which an abolition of protoplasmic activity is normally accom- 

 panied by a veiy large discharge of fluid and loss in weight and turgescence, that death 

 is not accompanied by any considerable diminution in weight or turgescence, and that the 

 dead tissues may persist for prolonged periods in a highly turgid condition. The follow- 

 ing experimental details illustrate very clearly the different effects produced on turgidity 

 of tissue where death is determined with or without the addition of osmotic materials 

 to the cell-sap : 



Experiment XIX. — Two leaves of Kalanchoe—ojie, a, weighing 28*22 the other b 

 27-54 grammes— were taken and set with the bases of the petioles immersed in water. 

 The lower extremities of the petioles were then cut off subaqueously, so as to permit of 

 free absorption, and leaf a set in a chloroform-chamber, and I in an ammoniacal one. 

 Copious sweating set in in a within half an hour, and advanced so rapidly that the lobes 

 had begun to collapse within an hour from the beginning of the experiment, the tissue 

 at the same time beginning to acquire a yellowish tinge. In the case of b. a Km 



ted 



amount of exudation appeared very rapidly, and the tissue acquired an intense deep green 

 tint, but no considerable loss of fluid occurred, and the leaf remained perfectly firm and 

 showed no signs of collapse. The ammonia appeared to act more rapidly 



in causing 



