58 Florence R. Sabin. 



lie external to the myotomes and open in part into the segmental 

 lymph hearts and in part into the axillary sinus, and (5 and 6) the 

 deep subvertebral lymph trunks. The subvertebral lymph trunks are 

 paired vessels with many anastomoses which extend from the tip of 

 the tail to a point opposite the stomach, where they unite to form a 

 cisterna chyli. From the cisterna chyli four vessels run forward to 

 the axillary plexus, the paired thoracic duct and the two paravertebral 

 lymph trunks. 



The axillary lymph sacs open by three or four branches into the 

 cardinal veins and receive the following vessels: (1) The lateral 

 superficial lymph trunks; (2) the paravertebral vessels; (3) the thor- 

 acic duct; (4) vessels of the cranial part of the stomach and esopha- 

 gus; (5) a vessel which runs in the groove between the pericardial 

 and peritoneal sacs; (6) a vessel which comes from the base of the 

 skull; (7) superficial vessels from the side of the head, and (8) the 

 lymph vessels of the forelegs. 



Besides the axillary sac there are two other sacs or sinuses, one of 

 which lies dorsal to the aorta at the base of the heart, namely, the sinus 

 lymphatieus cordis (Hoyer 49b, fig. 5), and is in the course of the jug- 

 ular lymph trunks and the other of which makes the paired sinus of 

 the inguinal region. 



The segmental lymph hearts receive three groups of vessels: (1) 

 branches from the subvertebral lymph vessels (which agrees with 

 the findings of Marcus 87a, in Gymnophionem ; (2) dorsal and ven- 

 tral segmental branches, and (3) the longitudinal lymph trunk. 

 They open into the vena lateralis. The segmental lymph hearts and 

 the sinus lymphatieus cordis have striated muscle in their walls. It 

 is clear that a knowledge of the origin of this system would be of 

 great value, as Hoyer says : " Erst wenn die beriihrten noch zweifel- 

 haften Punkte durch weitere Untersuchungen vervollstandigt sein 

 werden, wird eine gewisse Grundlage zu vergleichenden Betrachtungen 

 des Lymphgefassystems der niederen Wirbeltiere geschaffen sein" 

 (49b, p. 555). 



Stromsen (145) and Huntington (57) have worked on the de- 

 velopment of the lymphatic system in reptiles. Stromsen shows that 

 the posterior lymph hearts develop in relation to the coccygeal veins. 

 He describes the process as a combination of veins and dilated spaces 

 similar to Sala's decription for the corresponding hearts in birds. 

 This method of formation has now been disproved by the observation 



Digitized by Microsoft® 



