[Four bladders were first tried as a control experiment, in the manner just described, in a solution of one part of gum arabic to 218 of water, and two bladders in a solution of one part of sugar to 437 of water; and in neither case was any [page 414] change perceptible in the quadrifids or bifids after 21 hrs.  Four bladders were then treated in the same manner with a solution of one part of nitrate of ammonia to 437 of water, and re-examined after 21 hrs.  In two of these the quadrifids now appeared full of very finely granular matter, and their protoplasmic lining or primordial utricle was a little shrunk.  In the third bladder, the quadrifids included distinctly visible granules, and the primordial utricle was a little shrunk after only 8 hrs.  In the fourth bladder the primordial utricle in most of the processes was here and there thickened into little, irregular, yellowish specks; and from the gradations which could be traced in this and other cases, these specks appear to give rise to the larger free granules contained within some of the processes.  Other bladders, which, as far as could be judged, had never caught any prey, were punctured and left in the same solution for 17 hrs.; and their quadrifids now contained very fine granular matter.

A bladder was bisected, examined, and irrigated with a solution of one part of carbonate of ammonia to 437 of water.  After 8 hrs. 30 m. the quadrifids contained a good many granules, and the primordial utricle was somewhat shrunk; after 23 hrs. the quadrifids and bifids contained many spheres of hyaline matter, and in one arm twenty-four such spheres of moderate size were counted.  Two bisected bladders, which had been previously left for 21 hrs. in the solution of gum (one part to 218 of water) without being affected, were irrigated with the solution of carbonate of ammonia; and both had their quadrifids modified in nearly the same manner as just described,—­one after only 9 hrs., and the other after 24 hrs.  Two bladders which appeared never to have caught any prey were punctured and placed in the solution; the quadrifids of one were examined after 17 hrs., and found slightly opaque; the quadrifids of the other, examined after 45 hrs., had their primordial utricles more or less shrunk with thickened yellowish specks, like those due to the action of nitrate of ammonia.  Several uninjured bladders were left in the same solution, as well as a weaker solution of one part to 1750 of water, or 1 gr. to 4 oz.; and after two days the quadrifids were more or less opaque, with their contents finely granular; but whether the solution had entered by the orifice, or had been absorbed from the outside, I know not.