The Origin and Development of the Lymphatic System. 53 



C.L.D. 



Fig. 15. — After E. L. Clark. Lateral view of the jugular lymphatic plexus 

 of the right side of a chick embryo 14 mm. long after an incubation of 5 

 •lays and 20 hours. The measurement was the greatest length and was 

 taken after fixation. With a very fine canula (the lumen of the point being 

 about 15 /i in diameter) diluted India ink was injected under a binocular 

 microscope into one of the superficial lymphatic capillaries in the skin 

 between the fore and hindlegs. From here the ink filled the deep jugular 

 lymphatic plexus, and from there a few granules entered the vein through 

 five connections (C). The drawing was made with the help of a camera 

 lucida with a Zeiss binocular microscope (oculars No. 4, objective A 3 ). 

 Magnified 67 times. A. = vessel which connected the superficial lymphatic 

 capillaries with the jugular lymph plexus and which was injected; A. C. = 

 vena cardinalis anterior; P. C. = vena cardinalis posterior; D. C. = duct 

 of Cuvier; C. = communications between the jugular lymphatic plexus and 

 the veins: T. D. = deep lymphatic vessel; T. E. V. = vena thoraco-epi- 

 gastrica: C. L. D. = cervical lymph vessel. After E. L. Clark's fly. I, Anal. 

 Record, 1012, Vol. 6, p. 268. 



