Anatomy and Development of Posterior Lymph Hearts of Turtles. 81 



Mallory's connective-tissue stain is also very good. Many of the older 

 embryos had the blood-vessels injected with India ink. 



Embryos up to 26 days were imbedded in paraffin and cut 10// to 

 2o/( thick. Older embryos were cut by the celloidin method, about 25^11 in 

 thickness and mounted on lantern slides. One series of embryos was 

 cut into 50/^ sections, and another series of older stages was cut into 

 sections loojJ. in thickness. Wax and blotting paper, as well as graphic 

 reconstructions, were made whenever necessarv. 



ANATOMY OF THE POSTERIOR LYMPH HEARTS OF TURTLES. 



Lymph hearts were discovered in turtles by Joh. Miiller in 1839. 

 He describes them in the green turtle {Chelonia mydas) as a pair of 

 rounded organs, more or less flattened dorsoventrally, lying just caudad 

 of the upper end of the ilium, one on each side of the body. They rest 

 upon the origin of the semiten- 

 dinosus muscle of each side 

 and are bordered laterally by 

 the biceps and caudally by 

 the semimembranosus muscles. 

 Lymph channels from the pos- 

 terior extremities and caudal 

 portion of the body open into 

 their posterior ends. Their 

 pulsations are irregular, occur- 

 ring at the rate of 3 or 4 times 

 per minute, and are not neces- 

 sarily synchronous for the two 

 hearts. Their inner wall is 

 smooth and their cavity is free 

 and not broken by trabeculse 

 or septa, as it is in the land 

 turtle. The openings of the 

 afferent and of the efferent 



ducts are guarded by valves. They open, by means of a short duct, into 

 the vein that runs forward along their mesial border to become the pos- 

 terior renal advehent vein of each side. 



In the large land turtle (Testudo elephantina) , described by Fritsch 

 (1874), the lymph hearts are ovoid in form with a longitudinal diameter 

 of 38 mm. and a width of 20 mm. in the anterior half, and 15 mm. in the 

 posterior half. Their walls contain striated muscle fibers and are about 

 I to 2 mm. in thickness. Their central cavity, especially in the posterior 

 region, is broken up by septa and trabeculas. They open directly into 

 the ischiadic vein, and in the right heart a second opening communicates 

 with a small vein on the inner border of the heart. 



In the mud turtle, Chrysemys marginata, studied b}- the writer, the 

 posterior lymph hearts are found just beneath the carapace, immediately 

 caudad of the upper end of the iliac bones. They are somewhat elliptical 

 in form, but are slightly flattened dorsoventrally. 



6 



B 



Fig. I. — Diagram showing relations of posterior lymph 

 hearts to veins of pelvic regions of Chrysemys 

 marginata. ab, abdominal vein; as. azygos; p.r.a., 

 posterior renal advehent ; p, peroneal; c.i., circum- 

 flex iliac; i.fe., lymph heart; is, ischiadic; c.c, com- 

 mon coccygeal; s.c, superior coccygeal. 



