6 



Scientific Proceedings (50). 



direct ventral tracts are much larger than the other two and can 

 be traced as far as the lower sacral segments. The crossed lateral 

 and direct dorsal seem to disappear in the upper thoracic region. 

 Arranged according to the number of fibers which they contain, 

 the order is crossed dorsal, direct ventral, crossed lateral, direct 

 dorsal. 



5 (70i) 



Interpolated extra- systoles, of frequent occurrence, in an other- 

 wise normal human heart. 



By M. DRESBACH and S. A. MUNFORD. 



[From the Physiological Laboratory, Cornell University, 

 Ithaca, N. Y.] 



In the extensive literature upon extra-systoles about twenty 

 writers have described the type known as the interpolated beat 

 of the ventricle. Although such beats have frequently been pro- 

 duced experimentally, their occurrence clinically is comparatively 

 rare. 1 Almost without exception they have been observed in 

 cases showing gross lesions of the heart. The present case is of 

 interest because the interpolated contractions occur persistently 

 and frequently in a heart which, aside from a slow sinus rhythm, 

 is otherwise normal. It furnishes a striking example of an organ 

 on the borderland between a physiological and a strictly patho- 

 logical condition. 



T., a Chinese student at Cornell University, is in good health. 

 He is able to take vigorous exercise, such as running, tennis, etc. 

 About two years ago a cardiac irregularity was discovered in his 

 routine physical examination. Prior to that time he was wholly 

 ignorant of any disturbance in his heart, and is at no time conscious 

 of the heart's contractions. Polygraphic records have frequently 

 been made during the past two years and the organ has been found 

 beating normally on two occasions only, and but for a short time. 



The tracings show extra-systoles of the ventricle which occur 

 with considerable regularity 7 on some days, but usually they appear 

 at varying intervals. The normal rate of the dominant rhythm 



1 Mackenzie, Lewis, Wenckebach, and others. 



