78 FRANKLIN P. REAGAN 



press too closely to the entoderm. When the endothelium starts 

 to develop, the visceral mesoderm gives off mesially directed 

 folds, and perhaps at the same time invaginates in such a man- 

 ner as to conform to the contour of the endothelial tubes and 

 to engulf the latter by the mesial fusion of these folds. Such 

 funnels, in the heart region at least, are probably not concerned 

 with the production of endothelium, but rather in furnishing it 

 with a myocardial covering. The covering may be found around 

 a single tubular unilateral anlage; but in case the anlage be 

 branched, or a formation from venous rootlets, the branches or 

 rootlets may be provided individually with a myocardial cover- 

 ing. Such formations are probably in process in figures 28 and 

 29. Here it will be seen that each endothelial tube is partly 

 surrounded by myocardium. These facts are of interest in con- 

 nection with the phenomenon of multiple heart-formation which 

 is sometimes observed. 



For a number of years, cases of duplex heart-formation have 

 been known, and have been ascribed to various causes. Panum 

 explained double heart-formation on the assumption that a pull 

 on the bifurcated ventral aorta had torn asunder an already 

 formed heart. Rabl and others have attributed it to a failure 

 of the bilateral heart-anlagen to fuse into a single heart. Vari- 

 ous cases of multiple hearts have been observed. A most 

 unusual case is that described by Verocay in the proceedings 

 of the Deutsche Pathologische Gesellschaft, 1905. He described 

 a case of a chicken with seven hearts (Heptacardia) . At a hotel 

 in Cortina d'Ampezzo, an apparently normal fowl was found 

 on evisceration to contain a peculiar clump of tissue which when 

 further examined was found to contain seven hearts. Unfortu- 

 nately the specimen was badly mutilated. Later examination 

 of this clump of tissue by Verocay (73) revealed the fact that 

 five of the seven hearts were of normal shape and size. The 

 two which were removed from the rest exhibited normal rela- 

 tionships of heart-cavities, valves, and stems of the arterial 

 vessels. It was impossible to determine the relationships of the 

 great veins and the auricles. Verocay believed that each heart 

 had been provided with a separate pericardium of its own. It 



