author's abstract of this paper issued 

 by the bibliographic service, july 7 



THE DEVELOPMENT OF THE CARDIAC LOOP IN THE 

 RABBIT, WITH ESPECIAL REFERENCE TO THE 

 BULBOVENTRICULAR GROOVE AND ORIGIN OF 

 THE INTERVENTRICULAR SEPTUM 



HENRY A. MURRAY, JR. 



College of Physicians and Surgeons, Columbia University, N. Y. 



SEVEN FIGURES 



The process of union of the two lateral cardiac vessels to form 

 the heart has recently been described in detail by Doctor Schulte 

 as exemplified in the series of young cat embryos of the Columbia 

 Collection. It was at Doctor Schulte's suggestion and under 

 his supervision that I undertook to ascertain whether fundamen- 

 tally the same processes took place in the embryo rabbit. 



Earlier investigators had described how the lateral plexuses 

 of blood-vessels, forming into two longitudinal endothelial tubes 

 in the splanchnopleure, unite in the midline to create a cylin- 

 drical median structure — the heart; and they considered that 

 during subsequent growth the heart became coiled to accommo- 

 date itself within the pericardium. Doctor Schulte's investi- 

 gation, previously mentioned, showed that it was not such a 

 simple process, but that a number of very interesting factors 

 were responsible for the changes that took place. Through the 

 kindness of Dr. F. T. Lewis in putting at my disposal the beauti- 

 ful Harvard series of rabbit embryos and by his guidance and 

 suggestions, I was able to study the fusion and subsequent 

 history of the heart in another species. Approximately forty 

 embryos from the Harvard rabbit and Columbia cat series were 

 examined under the microscope and a dozen and a half models 

 were constructed in wax, according to the Born method. The 

 cat embryos were cut in 13.3/x sections, whereas the rabbits were 

 cut in 6/x or 10/z sections, mostly transverse. The thicker sections 

 are less apt to be damaged, pile into better models, and under 



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