233 DR. ORD. 



tablets were rounded at the ends^ thicker, often laminated 

 and compressed or constricted in the middle, indicating the 

 early stages of wheatsheaf formation. 



Reviewing the whole group of experiments, it is evident — 



1. That when deposited in gelatin, calcium oxalate assumes 

 many forms, including, besides the characteristic octohedron, 

 dumb-bells of two kinds, crystalline and homogeneous, tablets 

 and prisms of several kinds, and variously shaped calculi. 



2. That the octohedra, tablets, wheatsheaves, and crystal- 

 line dumb-bells appear to stand in direct serial relation to 

 one another ; the granules, calculi, and homogeneous dumb- 

 bells having among themselves a similar relation. Crystals, 

 however, may be resolved into homogeneous dumb-bells in 

 two ways — either by a formation of dumb-bell within the 

 outline of the crystal, or by total disintegration of the crystal, 

 which is converted in mass into a non-crystalline dumb-bell. 



3. That there is usually observed in the plugs a " line of 

 greatest deposit," corresponding, apparently, to the point at 

 which the diffusive force of the two solutions is balanced. On 

 the calcic side of this line homogeneous or " coalescence " 

 forms, on the oxalic crystalline forms, predominate. Excess 

 of oxalic or oxalates is favorable to the size and perfection of 

 the form generally ; with excess of calcic salt, the coalescence- 

 forms are immensely increased in numbers but decreased in 

 size. 



Where the oxalic acid predominates, crystals are mostly 

 broken up at their angles and laminated; Avhere calcic salt 

 predominates, they are flattened, drawn out at their angles, 

 feathered, or are small, perfect, and extremely symmetrical. 

 The causes which may produce these differences may be, and 

 are probably, of several kinds, namely : 



a. The formation of basic, neutral, or acid salts, according 



as the solutions balance or in turn prevail. 



b. The- formation of double salts. 



c. Alterations in the firmness or chemical constitution of 



the gelatin. It was generally noticed, in reference to 

 this, that the chloride of calcium tended to soften the 

 gelatin, the oxalic acid and oxalates to harden it. 



d. The presence of undecomposed salts of different solu- 



bilities Avould probably, in each case, tend to modify 

 the form in which deposit occurred. 



4. That in the first experiment the presence of calcium car- 

 bonate rendered the results different from those observed 

 when the presence of carbonic anhydride was avoided. And 

 here new questions arose : — Why should carbonate and oxa- 



