22 PROFESSOR D. J. CUNNINGHAM 



kindness I have been enabled to study a considerable number of stomachs which present 

 this pathological condition. He has likewise placed in my hands several microscopic 

 sections through the stenosed pyloric region of the infant. In addition to these, I have 

 had a number of other sections prepared by my assistant, Mr John Henderson. 



In pyloric stenosis the free and regular outflow of the gastric contents is prevented 

 by an abnormal condition of the pyloric canal. In this disorder the whole length of 

 the canal is involved, and any changes which may be apparent in the musculature of 

 the other parts of the stomach are merely secondary and compensatory to those in the 

 pyloric canal. 



The pyloric canal in such cases presents the appearance and has the feel of a hard, 

 solid cylinder, about f-ths of an inch in length. It is sharply marked off at its two 

 extremities from the duodenum on the one hand and the pyloric vestibule on the other. 

 In many instances the girth of the canal is not the same throughout its whole length ; 

 in the more extreme cases the canal narrows towards its two ends, and thus assumes an 

 oval or fusiform shape somewhat like that of an olive. 



All those who have made a microscopic examination of the pyloric canal in this 

 condition are agreed that there is an excessive development of the muscular coat, 

 although, from the different accounts which are given, it would appear that the relative 

 extent to which each of the two muscular layers is involved in this hypertrophy is not 

 the same in every case. A few examples selected from the voluminous literature of 

 the subject will best illustrate this point. Hirschsprung (21) states that relatively the 

 longitudinal fibres are the more strongly developed ; Finkelstein (13) gives an account 

 of a case in which the same layer was so strongly developed that it was chiefly respon- 

 sible for the muscular thickening ; in Gran's (16) case the hypertrophy was confined to 

 the circular fibres ; in Schwyzer's (48) case the longitudinal fibres were slightly 

 increased, whilst the circular layer was greatly hypertrophied. These observations are 

 sufficient to show that the musculature of the stenosed pyloric canal does not in every 

 case present the same features. At the same time, a glance through the literature 

 makes it evident that the usual condition in such cases is one in which both layers are 

 hypertrophied. 



The specimens submitted to me by Mr Stiles, as well as those prepared in this 

 department, show a great thickening of both the muscular layers. I would not venture, 

 however, to hazard a decided opinion as to whether they are both hypertrophied to 

 relatively an equal extent, or whether, as most observers believe, the circular sphincteric 

 cylinder has undergone the greater degree of thickening. Measurements do not give 

 reliable information on this point, because a large amount of the thickening is due to 

 contraction, and there are no means by which the degree of contraction in each layer can 

 be estimated. Speaking broadly, the thickness of the circular layer is from three to four 

 times as great as that of the longitudinal layer in the different specimens examined. 

 This would seem to indicate a relatively greater degree of hypertrophy in the longi- 

 tudinal layer, which, indeed, 1 believe to be the case. 



