208 



tion was not determined. Another, recently analyzed by myself, 

 is composed of carbonate of lime cliiefly ; with a little carbonate of 

 magnesia and traces of phosphate of lime and oxide of iron ; also, 

 animal matter, and sufficient silica to yield a porous, friable mass 

 when the other constituents are removed, I estimate the proportion 

 as about ^ of the weight of the calculus. 



X. A calculus from the bladder of a fresh-water turtle, analyzed 

 by Lassaigne in 1844. The chief constituent was phosphate of lime, 

 amounting to 56 per cent. ; 4| per cent, of silica occurred, in trans- 

 parent grains. 



XI. A large, ovoid calculus, removed by lithotomy from the blad- 

 der of a man. Analyzed by Wurzer in 1806. It contained 1 per 

 cent, of silica ; with about 75 of uric acid, 1 7 of phosphate of lime, 

 and animal matter. 



XII. A calculus, weighing nearly fifteen ounces, from the human 

 kidney. Analyzed by Koninck in 1836. The principal constituent 

 was triple phosphate, and the proportion of silica was I of one per 

 cent. 



I cannot learn that any of the above specimens have been pre- 

 served in any cabinet, except the five now exhibited. Three of these 

 belong to the Cabinet of the Boston Society for Medical Improve- 

 ment, and two to the Warren Anatomical Museum at the Harvard 

 Medical College. About a dozen additional instances are reported, 

 of the occurrence of a little silica, mostly traces only, in calculi from 

 the ox, the horse, and the human subject. All these cases are 

 noticed in my article in the Medical and Surgical Journal of last 

 June. 



Dr. Winslow alluded to the jet of fluid which he had often seen 

 escape from the green cocoanut, fresh from the tree, when the eye is 

 punctured ; this he believed was due to the pressure arising from the 

 upward motion of the sap, or vis a tergo. He did not think the nut 

 contained any gas. 



Dr. Bacon observed that such a jet might arise either from dis- 

 solved gas or a very elastic shell. 



Professor Agassiz thought that any pressure from below, or vis a 

 tergo, impossible in a nut with a hard shell and not in direct commu- 

 nication with the stem ; the inner meat becomes less and less soHd 

 from without inward, and in contact with the milk is very fluid ; as 

 the meat consists of cells, which would be most flattened by pressure 

 toward the circumference, perhaps the elasticity of these flattened 

 cells might explain the jet. 



Professor Rogers regarded the accumulation of a highly compressed 

 gas the most probable exjilanatiou. 



