198 The Blood-Supply of Lymphatic Vessels in Man 
vessels but slightly greater than this, witha capillary on either side of 
it. These accompanying capillary vessels are supplied and drained at 
many points by slender arterioles and venules and occasionally send a 
single connecting branch at right angles across the lymphatic. Such a 
simple scheme is figured in Fig. 1. This is frequently the only circula- 
tion possessed by lymphatic vessels until their caliber exceeds about thir- 
teen-hundredths of a millimeter (.13 mm.) in diameter. 
In the case of lacteals measuring between fifteen-hundredths (.15) 
and four-tenths (.4) of a millimeter in diameter it is almost always 
possible to find an accompanying artery and vein at least on one side of 
a Le, 
NS 
2) WV Dd rsa 
Zz 
ydkonnnnbd 
(QC QQanbacagvaqgaan ce a guns once td 
Bigs. TMs 2 
Fic. 1. Small lacteal in human mesentery, showing accompanying capil- 
laries on either side with cross branch. »X.-50. 
Fic. 2. Human lacteal two-tenths of a millimeter in diameter. The accom- 
panying artery and vein are seen and the capillary loops encroaching on the 
lymphatic wall. x 50. 
the lymphatic. From these vessels, slender capillary loops extend out 
towards the center of the lacteal wall and in most cases, extend at some 
place across it. Such a type of circulation is shown in Fig. 2. 
In lacteals from four to five-tenths of a millimeter in diameter and 
above this, the accompanying vessels have often a diameter of at least 
30 or 40 microns. Artery and vein, with little diminution of size, may 
be traced for relatively great distances, coursing with the lacteal. Often 
they are duplicated on the opposite side of the lacteal so that really four 
