Chap. XVTL] ABSORPTION BY THE QUADRIPIDS. 335 



cay. Therefore most of my experiments were made by cut- 

 ting bladders longitudinally into two; the quadrifids were 

 examined with No. 8 of Hartnack, then irrigated, whilst 

 under the covering glass, with a few drops of the fluid under 

 trial, kept in a damp chamber, and re-examined after stated 

 intervals of time with the same power as before. 



Four bladders were first tried as a control experiment, in the 

 manner just described, in a solution of one part of gum arable 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 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 dis- 

 tinctly 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 solu- 

 tion for 17 hrs.; and their quadrifids now contained very fine 

 granular matter. 



A bladder was bisected, examined, and irrigated with a solu- 

 tion 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) with- 

 out 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 examine<l 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 am- 

 monia. Several uninjured bladders were left in the same solution, 

 as well as in 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 solu- 

 tion had entered by the orifice, or had been absorbed from the out- 

 side, I know not. 



