Vermiform Appendix. 353 



Adult measureiuents (Morris) — 



Stomach .30 metres 



Small intestines - - - 8.00 „ 

 Large intestines - - - 1.40 ,, 



Appendix .10 ,, 



Caecum ----- .06 ,, 

 In tlie adult the proportionate increase of length from foetal 

 type is : — 



Stomach and small intestines - Eight times 

 Large intestines - - - About six times 

 Caecum and appendix - - Less than three times 



In the Joetus the caecal ratio is about one to tivettty-itvo ; in the 

 adiilt, about one to sixty-one. 



In studying the five human types we observe that the foetal 

 caecum is a relatively larger organ than an infantile caecum, 

 for this has become shortened by the pull of the muscle bands 

 which ai-e set into the muscle sheath, the sheath which in type 

 B becomes the appendix. From this stage in caecal atrophy the 

 miost easily followed atrophic process is that along the mesenterio 

 muscle band. This process enables the appendix to migrate from 

 the fundus of the caecum to the ileo-caecal valve — a migration 

 going on concurrently with general caecal atrophy. Figs, (type 

 B, Fig. 8. and type D, Fig 8.) 



The recession of the human caecum from large foetal type to 

 small adult type is marked by a peculiar variation in the 

 external muscle coat through which, by the pull of the muscle 

 bands on the muscle sheath, an appendix is formed. 



The five types of human caecum indicate that during modem 

 times caecal atrophy has been progressing at varying speeds, 

 due to sections of the race adopting foods of different bulk. 

 Rapid food changes have occurred concurrently with material 

 progress and increased transportation facilities. Those in type 

 D have been for a long period taking food of small bulk and 

 high nutritive quality ; those in type A have remained on the 

 bulkier food of their ancestors or a food more bulky than is 

 used by type D. Type C — the intermediate type — represents 

 the mean of these extremes ; it is the common type. Upon the 

 embryological principle " that the higher types pass through 

 stages during their development that are permanent in some 



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