38 Macfarlane. — Contributions to the History of 



began to pour out in nine hours from one, in eleven hours 

 from another, and in twelve from the third. In its behavior 

 it resembled the ordinary fluid. 



It thus appears that the secretion is entirely due to irrita- 

 tion of the protoplasm, and is poured out alike by mechanical, 

 chemical, and electrical stimulus. Now any irritant stimulus 

 applied to protoplasm causes rearrangement of its molecules. 

 In the doing of this work, decomposition of its substance 

 occurs with the setting free of decomposition products, either 

 into the cell cavity or outside the cell. The best and most 

 accurately investigated cases of this are derived from mus- 

 cular tissue among animals, where definite decomposition 

 products such as sarcolactic acid, carbonic acid, acid phos- 

 phate of potash and various nitrogenous compounds can be 

 detected. But in the secretion of Dioncea several products, 

 including some acid body, can be detected. Dr. T. A. G. 

 Balfour 1 states that Prof. Dewar determined the presence of 

 formic acid as well as various chlorides. 



Gardiner states that after absorption various new substances 

 can be observed, and says, "sections of leaves which were 

 placed in alcohol thirty-six hours after feeding show that the 

 cells contain a very large number of tufts of crystals, which 

 are present in the cell vacuole, and adhere to the inner sur- 

 face of the cell protoplasm. The tufts are formed of fine 

 acicular crystals, which crystallize out with great regularity 

 and radiate from a central point. The tufts are of a yellow- 

 green color. They are insoluble in alcohol, and in one per 

 cent, acetic acid. The formation of these crystals may be arti- 

 ficially produced by wetting the surface of a fresh leaf with 

 the fluid from a leaf which has fed for a period of from thirty- 

 six to forty-eight hours." Before perusing his account I had 

 experimented with the secretion and found the substance 

 described by him, but in all cases it crystallized out on addi- 

 tion of absolute alcohol with startling rapidity. Thus, when 

 a secretion-drop on a slide was placed under the microscope, 

 the secretion appeared glairy and indistinct as already de- 

 scribed, but a few drops of alcohol caused formation of the 



1 Transactions of Botanical Society, Edinburgh, Vol. XII, p. 34°- 



