TRANSACTIONS OF SECTION I. 809' 



The following Papers were read : — 



1. The Bhythm of Smootii Muscles. By Professor H. P. BowDiTcn. 



Gaskell (' Jourual of Physics,' iv. 118) has called attention to the fact that the 

 three sorts of muscle fibre recog-nised by physiologists — namely, striped, smooth and 

 cardiac fibres — are each characterised by the special development of a particular 

 form of activity, but that each kind of muscle possesses to a certain degree the 

 forms of activity which specially characterise the other kinds. Thus the power of 

 rapid contraction, which is most highly developed in striped muscles to serve the 

 purpose of locomotion, is possessed in a lesser degree by the cardiac, and in a still 

 less degree by the smooth muscles, whereas the power of tonic contraction, 

 strikingly manifested by smooth muscles, is much less marked in the cardiac and 

 striped muscles, and rhythmical contraction, which is the special function of the 

 cardiac muscle, is a phenomenon of subordinate importance in the smooth and 

 striped muscles. The following table represents the order in which the three 

 sorts of muscles stand with regard to the manifestation of the three forms of 

 activity. 



It is evident, therefore, that the phenomenon of muscular contraction may be 

 conveniently studied under the nine headings indicated in the table, and in this 

 communication the author desired to call attention to a few observations which he 

 has made under one of these headings — viz., that of the rhythmical contraction of 

 smooth muscle fibres. Many of the observations which are here referred to were 

 made ten years ago hy K. W. Lovett, but have remained unpublished hecause the 

 complicated nature of the phenomenon rendered positive conclusions difficult to 

 draw. The material used was a set of three rings of muscular tissue, one or 

 more mm. in width, taken from the cardiac, the middle, and the pyloric portion 

 of the stomach of the frog by sections perpendicular to the axis of the organ. 

 These rings were attached to the recording apparatus by metal hooks, which served 

 at the same time as electrodes, though in the experiments to be reported no 

 electrical stimulation was used.' 



The curves were traced upward on the smoked surface of a cylinder which 

 could be adjusted to revolve once in a hour, or once in twelve hours. The method 

 of procedure was in general to take the tracing during an hour with the more 

 rapid movement of the drum, and then to shift the cylinder on to the slower 

 movement. 



The results of Dr. Lovett's observations may be summarised as follows : — 



1. About 50 per cent, of the preparations manifested spontaneous activity as- 

 soon as they were attached to the apparatus. 



2. In about 13 per cent, of the observations the beginning of the activity 

 occurred after a period of 20 sees, to 3 hours. 



3. In 7 per cent, of the cases the delay was more than 3 hours. 



4. Thirty per cent, of the preparations remained inactive. 



5. Cases of delayed activity and of total inactivity were more frequent in tha- 

 middle and pyloric than in the cardiac portion of the stomach. 



' This method is the same as that employed by Morgen (^Untersuchungen, a.d. 

 I'lnjs. Inst. Univ. Halle Heft, ii. p. I3!l, 1890) in studying the irritability of smooth' 

 muscles. It is to be noted, however, that in Morgen's experiments spontaneous 

 movements of the stomach ceased after about twenty minutes, while in Dr. Lovett's- 

 experiments they lasted many hours. 



