80 Mr J. G. Adami, On the action of the [May 12, 



then, removing the clamp, to pass the wire down through the 

 mitral orifice and hook it over the edge of the mid-portion of one 

 of the valve flaps. This operation required a certain amount of 

 practice; the form of the curve shewed when it had been rightly 

 performed. Attached in this way the hook pulled upon the free 

 edge of the valve, and so through the chordae tendineaj upon the 

 papillary muscles, while the wire moved freely to and fro through 

 the collar inserted in the auricular wall ; there was little or no 

 disturbance by clotting. The two levers recorded simultaneously 

 upon the revolving drum, the one the contraction of the ventricu- 

 lar wall, the other the approximation and separation of the base of 

 the columna carnea and the edge of the mitral valve, that is to 

 say, the contraction and expansion of the papillary muscle. 



Tracings so obtained shewed that the papillary muscles begin 

 to contract and pull upon the mitral valves at a very definite 

 interval after the commencement of the ventricular systole, indeed 

 the interval between the two is so well marked that the papillary 

 curves frequently exhibit an initial depression, due it would seem 

 to an actual stretching of the papillary muscles and separation of 

 their bases from the edges of the valve, the increased blood 

 pressure within the ventricular chamber acting upon the valve 

 and tending to drive it upwards into the auricular cavity. This is 

 followed by the rapid contraction of the papillary muscles, which 

 in its turn affects the curve obtained from the ventricular wall. 

 Up to the moment when the papillary contraction begins, the lever 

 point registering the heart-wall curve had ascended rapidly and 

 in an almost straight line ; but now the ascent is slowed, and at 

 times there may be a slight depression or actual notch on the 

 upstroke. This does not indicate that there has been an inter- 

 ference with the act of contraction on the part of the heart- wall, 

 but that the shortening of the contracting muscles has been inter- 

 rupted, and this lessened shortening is due to the sudden increase 

 in the intra- ventricular blood pressure consequent upon the papil- 

 lary contraction. Small in bulk as they are compared with the 

 heart- wall, the musculi papillares by pulling upon the large flaps 

 of the mitral valve must exert an influence upon a very consider- 

 able proportion of the surface of the ventricular cavity, and their 

 contraction must have a distinct effect upon the intra-ventricular 

 blood pressure. That this is the case is rendered evident by a 

 comparison of the heart-wall curve with the curve of intra-ventri- 

 cular pressure. The slowing or depression upon the upstroke of 

 the former corresponds in time with a very well-marked rise or 

 secondary wave upon the latter, and it is this sharp rise of pres- 

 sure due to the contraction of the papillary muscles that hinders 

 for the time the shortening of the muscle fibres of the wall of the 

 ventricle : these fibres suddenly receive, as it were, an extra load, 



