REACTION OF LYMPHATIC ENDOTHELIUM 435 



tended in the direction of the fat and soon came into contact 

 with the surrounding leucocytes. When the rapidly absorbed 

 emulsions of cream and yolk of egg were the substances employed, 

 this sending out of fine processes was the only noticeable growth 

 reaction on the part of the lymphatic. On the other hand, when 

 the injected material happened to be olive oil or oleic acid, the 

 new processes of the lymphatic persisted longer and acquired a 

 lumen. Once, a forked process was sent out which enlarged, 

 acquired a lumen, and extended on either side of the oil, in close 

 contact with the rim of leucocytes, as two branches of the 

 lymphatic. 



When the injected substance was made at a distance from a 

 lymphatic, the reaction was much more striking. A finely 

 pointed process was sent out from a nearby lymphatic, which 

 grew out in the direction of the injected fat. This process in- 

 creased rapidly, in length, acquired a lumen and grew further, 

 soon outdistancing the other lymphatic and blood vessel sprouts 

 of that part of the tail. In case the substance injected did not 

 chance to be one of the rapidly absorbable emulsions, this new 

 lymphatic capillary grew directly toward the site of injection and 

 came into close contact with the oil or soap and its surrounding 

 leucocytes (fig. 2). In figure 2 is given a series of records 

 illustrating the growth of a lymphatic sprout toward an injected 

 globule of olive oil. It will be seen that the lymphatic tip grows 

 directl}^ toward the oil and reaches it two days after the injec- 

 tion, having grown a considerable distance during that period. 

 In the first record, made immediately after the injection, the 

 lymph capillary is seen to be much shorter than the neighboring 

 blood capillary. In the last record, made after the lymphatic 

 has reached the globule, the lymph sprout is almost twice as 

 long as the blood vessel, the latter having retracted during the 

 observation. 



In another series of observations (fig. 3) a globule of olive oil 

 was injected to the left of a lymphatic and some distance away. 

 A drawing, made immediately afterward, showed that the tip 

 of the lymphatic was pointed toward the right and away from 

 the oil globule. A blood vessel was present at the left of the 



