IN THE MOTOR OK( V.NS OF LK.WKS. 



27 



any living protoplasm. During the process of maturation, the protoplasts of the cells 

 have been gradually expended with a proportionate accumulation of the products of 

 their functional activity in the cell-sap; and in the fully ripened tissue, if any living 

 protoplasm persists, its amount must evidently be extremely small. Wliatever its amount 

 be, however, it certainly is not the cause of the turgidity of the tissue, as we 

 find the latter persisting under cireuim am-es which involve the death of any living 

 protoplasts which have been exposed to them. When, for example, we expose portions 

 of the mesocarp of an orange to the influence of the conditions which wo have just |< < Q 

 to cause loss of turgescenco where the latter is dependent on the presence of living 

 protoplasts, we do not find any evidence in these portions of the ot urrence of 

 parallel change. This is shown by the results of the following experiments: 



Experiment XIV. — A segment of the mesocarp of a ripe orange, weighing 10*58 

 grammes, was exposed in a chloroform-chamber for twenty- four hours. At the close of 

 this period it weighed 10*G grammes and retained its turgidity unaltered. 



Experiment XV. — A segment, weighing 9*">2 grammes, was exposed in a chloro- 

 form-chamber for twenty-four hours. At the close of the experiment it weighed 9* 3 



grammes. 



Experiment XVI. — A segment, weighing 13*5 grammes, was immersed for forU 

 minutes in a 2*5 per cent, alcoholic solution of corrosive sublimate. On removal its 



weight had increased to 13*73 grammes. Jt was now placed in a simple moist chamber, 

 and on the following day was found apparently just as it had been at the beginning 

 of the experiment, quite turgid, the surface dry, and the weight 13*5 grammes. . 



* 



Experiment XVII, — A segment, weighing 2044 grammes, was immersed in a 2*5 

 per cent, solution of corrosive sublimate for twenty-four hours. At the close of that 

 period it was excessively turgid, and when dried weighed 20*04 grammes. It w i 

 now placed in a simple moist chamber. Twenty-four hours later it was quite turgid, 

 the surface dry, and the weight 19*87 grammes. It was kept under observation for 

 three days longer, and at the end of the experiment weighed 19 5 grammes. 



Experiment XVIII.— A segment of the mesocarp of a ripe orange (a), weighing 

 13*08 grammes, and a leaf of Kalanchoe (b), weighing 17*24 grammes, were immers I 

 for one minute in boiling water. On removal (a) weighed 13*5 grammes and (b) only 

 15*65. Forty-eight hours later, (a) weighed 12*54 grammes; whilst (b) was flaecid, 

 yellowish olive, and weighed only 14*6 grammes; the total loss in the former amounting 

 to 4*1 per cent, and in the latter to 15*3 per cent. 



One of the most striking examples of the maintenance of an extremely high 

 degree of turgidity in cells, independent of the presence of any continuous stratum of 

 living protoplasm, is that which is afforded by the fertile filaments of Pilobolus crystal- 

 linus. The excessive turgescence in these, which ultimately leads to their rupture and 

 the violent discharge of the sporangia, arises only after they have been almost entirely 

 emptied of protoplasm by the onward progress of the latter and its accumulation within 

 the sporangium, and certainly when no continuous stratum invests the interior of the cell 

 wall. It is certainly, therefore, independent of any anti-filtrative property of protoplasm, 

 and indeed is apparently independent of the action of any local protoplasm altogether, as 

 we find it to bo present in cases in which even the lower part of the stem immediately 



Ann. Eoy. Bot. Gard. Calcutta Vol. VI. 



