452 STANHOPE BAYNE-JONES 



found suhendothelial clumps of bacteria in the heart valves, 

 with hemorrhages within the structure of the valve. Rosenow 

 thinks that the localization of bacteria in the valve must depend 

 upon the presence of small blood-vessels there, which become 

 embolized by clumps of bacteria. 



The most recent sununary of the controversy has been placed 

 by MacCallum (11) in his ''Text Book of Pathology." His own 

 studies of the subject make him take position with Langer — 

 limiting the vessels to the basal third of the atrio-ventricular 

 valves. MacCallum states: a ''very complete injection of the 

 dogs' heart can be made by clamping the aorta and injecting 

 India ink into the carotid before the heart stops beating." My 

 experience has been that the heart of the dog is not good ma- 

 terial to use for such a study, and that an injection mass pushed 

 by the pressure of a failing heart-beat has entirely too slight a 

 force to penetrate the vessels of the heart-valves. Proper 

 pressure, suitable injection mass and the study of cleared speci- 

 mens are the factors to which I attribute the findings to be 

 recorded here. 



EXPERIMENTAL STUDIES 



The method of demonstrating the blood-vessels in the heart- 

 valves was based upon the injection of a solution of carmin- 

 gelatin into the coronary arteries. In some cases, as Dr. M. C. 

 Winternitz has pointed out, vessels are visible in the valves of 

 hearts opened at autopsy. It is a relatively simple matter to 

 insert a capillary glass pipette into these vessels and to inject 

 their fine ramifications with India ink. In this way, how^ever, 

 lymphatics are not distinguishable from blood-vessels. Injec- 

 tions through the coronary arteries, on the other hand, give 

 unequivocal evidence of the type of vessel thus filled with the 

 colored mass. 



The carmin-gelatin used in these injections w^as prepared as 

 follows : 



GeloMn: a 15 per cent, solution of gelatin (gold label) was 

 made by slowly dissolving the requisite amount of gelatin in 

 distilled water over a steam bath. When this was thoroughly 



