The Experimental Production of Gall Stones 129 



excellent condition, but the observations on several of them were 

 cut short by calculus formation in the collecting system. Twelve 

 dogs have been studied with relation to this development. Calculi 

 were found in six, and in three of these the bile had been sterile. 

 In two of the three instances, the calculi gradually filled the 

 2 mm. lumen of a glass canula on the wall of which they were 

 sessile, and gave rise to obstruction. Once this happened within 

 twenty-one days of intubation. 



The calculi were found only on the walls of the collecting 

 system of rubber and glass, never in the ducts themselves; and 

 they occurred in none of five instances in which this system 

 remained clear of organic debris (dead cells and mucinous mat- 

 ter), but in six out of seven in which there was lodgment of such 

 material, — from which the ducts were always practically free. 

 The stones were multiple, discrete, — at least to begin with, — of 

 approximately the same size at any given level in the tube sys- 

 tem, but larger toward the glass canula inserted into the common 

 duct, and more numerous and larger on the lower side of the 

 tube lumen and wherever there existed the possibility for an 

 eddy in the bile current or a dead space, as where glass and 

 rubber joined. The calculi that had formed on the glass connec- 

 tions could be examined directly with the microscope. Earlv 

 stages were studied in this way. 



The stones were made up of calcium bilirubinate and calcium 

 carbonate, with a scaffolding of organic material. Cholesterol 

 was not demonstrable in them. The majority had a center of 

 calcium bilirubinate surrounded by an envelope of crystalline, 

 slightly pigmented carbonate ; but stones consisting almost wholly 

 of one or the other substance were encountered. Frequently a 

 number of pigment stones were secondarily united in a matrix 

 of carbonate. The relation of the calculi to the organic debris 

 associated with them differed significantly. Those formed pri- 

 marily out of carbonate originated in the midst of lumps of the 

 debris, as the microscope showed, whereas the minute pigment 

 stones were so situated as to suggest that they, or their original 

 nuclei, had once been free in the bile but had been caught in the 

 debris and retained. Some of the pigmented calculi were large 

 and of such shape as to leave no doubt that deposition had 

 occurred upon them in situ. 



The relation between calcium bilirubinate and calcium car- 



