THE ALIMENTARY CANAL AND ITS APPENDAGES 169 



with accompanying very decidedly retrogressive changes (patho- 

 logical cases excluded) in the related tissues. 1 



Taking only adults into consideration (i.e. omitting individuals under 

 twenty years of age in whom variations are comparatively rare), out of 100 

 vermiform processes 32 were found partially or wholly closed. Complete 

 occlusion throughout the whole organ was found in a very small number, 

 about 3 1 per cent. Partial occlusion is much more frequent, all degrees 

 being found, from the first narrowing to the complete closing of the lumen. 



FIG. 101. THE CCECCM AND VERMIFORM PROCESS IN A KANGAROO. 



i.l., large intestine ; i.s., small intestine, v.i.c., position of the ileo-colic valve ; cce., 



ccecum. 



In rather more than half of the cases the occlusion affected a quarter of the 

 length ; in nearly half of the remainder its extent varied between one 

 quarter and three quarters, and in only a very small number did it affect 

 more than three quarters, or close up the tube. 



This process of occlusion is equally marked in both sexes, 

 and the statistics concerning its occurrence at different ages are 

 very striking. They make it clear that there is marked increase 



1 Actual pathological obliteration, nevertheless, occasionally occurs at the end of 

 the vermiform process. 



The occlusions which result, and which are probably always due to inflammation, 

 are less frequent than the typical obliteration (Ribbert). 



I cannot again in this connection refrain from referring to the coincidence of the 

 existence of vestigial organs and the tendency to disease caused by them. 



