38 American Quarterly Microscopical Journal. 



exudation cylinders or tube-casts. Nor were the microscopic 

 appearances of the organ those of inflammation. 



Within six weeks I had an opportunity of examining the 

 kidneys of two other patients dead from pneumonia, without 

 previous history of renal disease. In each case the urine con- 

 tained a small quantity of albumen, but no casts, and in each 

 instance colorless corpuscles were found in abundance in the 

 intertubular tissue, and in the malpighian capsules. At a 

 meeting of the West Chicago Medical Society, held June loth, 

 I exhibited a section from one-of these kidneys, and another 

 from a normal kidney, demonstrating to the satisfaction of 

 those present the existence within the connective tissue of the 

 former organ of the small round cells above described. At 

 that time I had sought unsuccessfully for literature or a refer- 

 ence to literature on this subject. However, deeming the fact, 

 if it were a fact, of the migration of leucocytes in passive 

 hyperaemia a very important one pathologically, I determined 

 to investigate the case, and for that purpose instituted the pro- 

 ceedings about to be narrated. 



On June 19th, I curarized a frog, cut down on the femoral 

 vein (which can readily be done without injuring the artery, as 

 in this animal the vein and artery lie on opposite sides of the 

 femur), made compression by means of a rubber band and a 

 plug of cork, and stretched the web of the corresponding foot 

 on the stage of the microscope. I employed a Hartnack No. 

 4 objective, and a Grundlach C periscopic eyepiece. By 

 watching the blood movements I easily regulated the pressure 

 so as to retard more or less completely the onward movement, 

 avoiding complete stagnation. After considerable compression 

 had been exerted, as was shown by accumulation of blood 

 corpuscles, distension of the vein, and retardation of the cur- 

 rent, the field was carefully watched for nine hours. During 

 that time no leucocytes were actually observed to leave the 

 vessels, yet several were seen just external to the walls, having 

 apparently escaped unnoticed during the shifting of the stage. 

 For the next ten hours the field was not observed with suf- 

 ficient care and frequency to warrant any assertion of migra- 

 tion. At the end of this period, "however, that is, nineteen 

 hours after compression was made, an almost continuous observ- 

 ation of the field was begun. From the 19th to the 36th hour leu- 

 cocytes were observed to leave the vessels in considerable num- 



