REACTION OF LYMPHATIC ENDOTHELIUM 429 



appeared to be larger than the cells which took them in (fig. 6). 

 On successive days, such a globule inside of a leucocyte, dimin- 

 ished in size and simultaneously the minute fat droplets and 

 brown pigment in the cells increased, apparently showing that 

 the oil globule was being resolved into a finer and finer emulsion. 



The injected globules of olive oil diminished slowly but steadily 

 in size but they were not completely absorbed at the end of 

 nineteen days. 



No reaction toward the injected olive oil on the part of blood- 

 vessel endothelium or mesenchyme cells was noted in any of the 

 observations. 



2. Oleic acid. This substance was injected in the same man- 

 ner and amount as the olive oil. Within a minute or two after 

 coming in contact with the intercellular fluid, the oleic acid 

 changed from a clear refractile globule to an opaque granular 

 mass with irregular margins, which was brown by transmitted 

 and white by reflected light. It was suspected that the oleic 

 acid had been combined to form a soap. In order to be reason- 

 ably certain of this, hard and soft soaps were made by boiling 

 oleic acid with sodium hydroxide and potassium hydr.oxide re- 

 spectively. The sodium oleate thus produced was found to have 

 the same microscopical appearance as the changed oleic acid, 

 while the potassium oleate differed markedly. It, therefore, 

 seemed fair to assume that the oleic acid is combined with 

 sodium of the tissue fluid to form the soap, sodium oleate, and 

 that, instead of oleic acid, we are studying the reactions of the 

 tissues to its sodium soap. 



The leucocytes responded to this substance more quickly and 

 in larger numbers than in the case of the olive oil. They mi- 

 grated toward the injected mass, formed a ring around it, sev- 

 eral layers deep, and soon became deeply pigmented. On the 

 day following the injection, many small refractile droplets were 

 visible near the point where the oleic acid had been injected. 

 These were scattered through the opaque brown mass and in 

 the area around it and superficial to it. Such droplets were not 

 present in other parts of the tail. The leucocytes surrounding 

 the injected mass also contained these refractile drops in addi- 



