FrSIOX OF CARDIAC ANLAGES IN THE CAT 



51 



veiitricLihir sulcus. Caudad the mantles diverge and pass into 

 the lateral mesocardia with a gentle curve. A distinct angula- 

 tion at this point is not apparent until the stage of 11 somites. 



On account of the obliquity of the myoepicardial mantles, a 

 triangular interval with its base at the anterior intestinal portal 

 is left between them. This is bridged by the residue of the 



Fig. 2 Photomicroo;raph of a cat emliryo of nine pairs of somites. Colunilna 

 Collection, Xo. 532. X 125. Reduced one-half. /, Ventricular segment of 

 mantle; 2, middle cardiac plate. 



precardiac plates after the closure of the foregut and the dis- 

 appearance of the ventral mesocardium. It may be designated 

 the middle cardiac plate. 



Between the bulbar segments it is narrow in this differing 

 from the rabbit (Strahl and Carius), but caudad attains a con- 

 siderable width (fig. 2). It is seen to agree in thickness and in 

 the character of its cells with the myoepicardial mantles and 

 like them to project entadin numerous longitudinal ridges, here 

 shown in cross-section. These ridges as elsewhere in the splanch- 

 nopleure are intimately related to the formation of mesenchyme 



