244 



Dr. W. Ord. Experiments on the 



[June 19, 



crystalloid is probably one reason why the metamorphic changes are 

 more rapid and are pushed further than in urinary calculi. 



There is, of course, a considerable variety in the proportions of the 

 various structures in these biliary calculi. Sometimes a gallstone shows 

 entirely a radiating structure. It is then usually but little stained 

 with pigment. Sometimes it is nearly all concentrically marked ; the 

 pigment is then abundant. I have throughout spoken more of the 

 pigment than of the mucus as the modifiying colloid, since the 

 examination certainly brings it into greater prominence ; just as I 

 have elsewhere shown that the chemically allied pigment of urine 

 exercises a parallel effect upon the form of uric acid, by preventing 

 that substance from assuming the rectangular form proper to it in its 

 pure state. The calculus is to all intents and purposes a dead thing 

 within the living body, yet it is of great interest to consider that it is 

 the seat of slow metamorphic changes, and that these changes are 

 effected in and by substances characteristically belonging to animal 

 life, and that they simulate processes seen in living structures, pro- 

 cesses that have been regarded as purely vital and dependent upon 

 the influence of cells or nuclei. 



I have next to speak of some allied phenomena exhibited by uric 

 acid. That substance, under certain modes of treatment, manifests a 

 succession of colloid and crystalloid states and attributes parallel on 

 the one side with those of the colloid pigment on the other with those 

 of the crystalloid cholesterin. 



Experiment 8. — If some uric acid be boiled for some time with 

 strong solutions of chloride of sodium or of phosphate of soda, and 

 the solutions be left after filtration to crystallise, urate of soda is de- 

 posited. But not in crystals. The fluid, after being thoroughly 

 cooled, is seen to be nearly filled with a semi-transparent gelatinous- 

 lookiug deposit, reminding one of the mucus separated from the urine 

 of early vesical catarrh. This deposit consists, as seen under the 

 microscope, of a gelatinous-looking matrix through which a number of 

 bright but as yet formless points are scattered. After a few hours a 

 slight diminution of bulk is apparent, and the microscope then shows 

 spherical arrangements of bright granules, and bright spherical tracts 

 without structure suspended within the jelly, the bright granules 

 being still present. Slowly, from day to day, the bulk of the pre- 

 cipitate grows less, and it gradually assumes a whitish instead of a 

 transparent aspect. The spherical bodies are gradually resolved into 

 spherical tufts of needles radiating from a common centre ; the matrix 

 becomes more and more granular. At last only a little white powder 

 is left lying at the bottom of the liquid ; it contains no trace of 

 matrix, and consists entirely of needles, some in tufts, some loose 

 This condition is not attained in temperate weather before the end of 

 a fortnight or three weeks. 



