26 C. W. M. Poynter 



2. Accessory Septum in Right Ventricle 



These cases are characterized by a septum in the upper part of 

 the ventricle. They are related to the preceding group in that 

 the developmental disturbance is of the conus, they differ in that 

 the conus may develop proportionately with the rest of the ven- 

 tricular wall and a portion of the bulb about the bulbar orifice 

 fails to drop out. When the conus is large and the bulbar orifice 

 is small the condition has been referred to as " three ventricles." 



Chassinat (1836), Husson (1836), Pegne (1847), Peacock (1869) 2 

 cases, Peacock (1876), Crocker (1878) (1879), Mackenzie (1879) 2 cases, 

 Nixon (1879), Lees (1880), Kleinschmidt (1881), Stone (1881), Toupet 

 (1883), Mackenzie (1889), CasseU (1891), Ruge (1891), Wendle (1898), 

 Young & Robinson (1907) 2 cases, Cautley (1908), Black (1914). 



D. LEFT VENTRICLE 



I. Contracture of the Left Ventricle 



There is difficulty in accounting for the stenosis of the left 

 conus as a simple developmental defect. As already stated the 

 literature shows that congenital disturbances have a marked predi- 

 lection for the right half of the heart; Rauchfuss stated that the 

 relation of lesions between the right and left sides was as 10: i. 

 Keith thinks that only a small portion of the bulb is incorporated 

 in the left ventricle, so left contractures are not quite comparable 

 to those of the right side. If we consider these cases as a simple 

 arrest of development of the ventricular chamber, as has been 

 suggested, and as has been accepted for the last of the preceding 

 group (contracture of right ventricle), then the left chamber 

 seems to be more prone to mal-development than the right. It 

 seems to me probable that the following list contains more cases 

 in which the bulbar element is responsible for the stenosis than 

 those of arrest of development of the primary ventricular cham- 

 ber; it seems, however, that this question cannot be settled by 

 examination of the specimens. Even in the cases of an anular 

 thickening of the ventricular wall just below the orifice of the 

 aorta it is difficult to distinguish the congenital cases from those 

 of stenosis due to endocarditis. 



