1885.] Mr F, W. Oliver, On the Transpiration' Current, <bc. 323 



tension produces a long musical sound. The relation between the 

 two kinds of sound is very suggestive of the relation between the 

 second and first heart-sounds. 



Since the cardiac muscle can produce a contraction sound, it 

 is evident that it must contribute a share to the first heart-sound, 

 although it may not be an important factor. If it were important, 

 the sound of a hypertrophied heart should be loud, whereas ex- 

 perience shews the opposite to be the case. The sound of the 

 muscle is probably not a prolonged one, but simply a dull thud: 

 and, since the muscle must contract before any other systolic event 

 can take place, the muscular thud must come at the beginning of 

 the systolic sound, not prolooging it towards the end as usually 

 supposed. The booming prolongation of the sound is most likely 

 due to the vibration of the valves and chordae tendineae under 

 the sustained tension to which they are subjected ; as simulated 

 in the experiments on stretching membranes. 



The systolic sound in small animals (cat, rat, mouse) is not 

 prolonged as in man and other larger animals. The two sounds 

 in small animals are nearly alike. The conditions which give the 

 special characters to the systolic sound in the human and other 

 large hearts, appear to be (1) the long systole with sustained 

 tension, (2) the large size and consequent free vibratility of the 

 valves and chordae tendineae, and (3) the thickness of the ventricle- 

 wall, which is not favourable to sharp vibration in itself, and which 

 acts as a partial non-conductor to the valvular sound. The simi- 

 larity between the two sounds in small hearts should therefore be 

 owing to the absence of these special conditions. 



(4) On the travelling of the Transpiration Current in the 

 Crassidacece. By F. W. Oliver, Trinity College. 



In this communication the author drew attention to some 

 experiments carried out by him on certain members of the order, 

 which would point to the importance of the living, cells of the 

 wood in the. ascent of the sap. The cooperation of the living 

 elements has been already shewn to be logically necessary by the 

 physiologists Godlewski and Westermaier ; and from the experi- 

 ments described some support for their general theories was 

 attempted to be drawn for a special case. 



(5) On the constitution of the walls of vegetable cells and the 

 degeneration changes occurring in them. By Walter Gardiner, 

 M.A., Clare College. 



The author stated that although a wall consisting entirely of 

 unaltered cellulose may conveniently be regarded as the typical 

 cell- wall, yet practically such a structure is seldom met with in 



