i897. NOTES AND COMMENTS. 8i 



(the history of fox-terriers, and refused to see in it any relation to 

 •dachshunds. Obviously, the difficulties of getting evidence that shall 

 exclude reversion, are very great in strains so sophisticated as those 

 of modern dogs ; but in so doubtful a subject, the investigation of 

 •every possible case is advisable, and we are glad to learn that Mr. 

 Latter has set going further experiments on the subject. 



The Function of the Intercostal Muscles. 



The precise action of the intercostal muscles has been the subject 

 •of much dispute amongst physiologists. The simple and diagrammatic 

 arrangement of hinged rods connected by crossed indiarubber bands, 

 which Huxley's "Elementary Physiology" has rendered familiar to us 

 from our youth up, has been recognised as a somewhat incomplete 

 representation of the complex movements of the ribs in respiration. 

 Some waiters have declared their belief that the intercostal muscles 

 play no important part in that act, and indeed so recently as 1894 

 Weidenfeld, as the result of experiments on dogs, maintained that 

 they remained completely passive even in extreme dyspnoea. It is, 

 however, admitted by almost all physiologists that the external 

 intercostals and the intercartilaginous portions of the internal 

 intercostals are inspiratory in function, acting synchronously with the 

 •diaphragm, though Masoin and Du Bois-Reymond found that, in the 

 case of the intercartilaginei, this was only the case in forced 

 inspiration. The action of the main mass of the internal intercostals, 

 on the other hand, has been much less certainly recognised ; they 

 'have been claimed as inspiratory muscles, though the opinion has 

 teen gaining ground that they are expiratory in function. Martin 

 and Hartwell have in recent years maintained this, and indeed the 

 fact that they contract alternately with the diaphragm makes it 

 highly probable. 



During the past year Messrs. K. Bergendal and P. Bergman 

 ■published in the Shandinavischen Archiv filr Physiologie (vol. 7, 

 :pp. 178-185) the results of a series of experiments carried on by them 

 in Stockholm, on the action of the intercostals in rabbits, dogs, and 

 ■cats. These seem conclusively to show that, in these animals at least, 

 respiration can be carried on by the intercostal muscles alone, after 

 the extirpation of all other respiratory muscles except the triangularis 

 sterni, and that while the external intercostals and the inter- 

 cartilaginous portions of the internal intercostals are inspiratory in 

 their action, the interosseous portions of the latter are no less clearly 

 expiratory. The experiments were carried out on narcotised animals, 

 and tracheotomy was performed as a preliminary in case artificial 

 respiration became needful during the course of the experiment. On 

 exposing the external intercostal muscles and severing them from 

 their lower attachments to the ribs, they were seen to contract 

 ^visibly during inspiration, and the same was true of the intercartilaginei. 



