DIGESTIVE SYSTEM 129 



Lieberkiihn's glands are completely absent in the fishes, but 

 from the amphibians upwards are to be found in the large in- 

 testine of all vertebrates. In man, as also in the mouse, rat, 

 squirrel and bat, the fundus of the Lieberkiihn glands contains 

 cells different from those which envelop the villi. 1 In man, 

 between every two villi occur from three to seven Lieberkuhn 

 glands from O'2 to 0-3 mm. in length. Only in man and the 

 mammals are Brunner's glands present. In man as in many of 

 the mammals these glands are most numerous in the neighbour- 

 hood of the pylorus. In the carnivora they cease immediately 

 below the stomach : 



In the horse . . 7 to 8 mm. "i 



, ,, ,r below the 



cattle . . i ., 6 > 



,, . stomach. 2 



the pig . . i 4 j 



The nodule or follicles which occur in the mucous membrane 

 of the small intestine, either isolated, or in groups, are most 

 abundant in the duodenum and ileum ; they are present also, 

 though to a lesser extent, in the fishes and amphibians, undergo 

 further development in the apes and birds, and attain their 

 highest perfection in man and the mammals. 



The isolated follicles measure : 



In man .... O'6 to 3 mm. 

 the horse . . . 2 4 

 cattle . . . 2 4 



In the sheep, goat, dog and cat the isolated follicles are 

 considerably smaller. 3 Peyer's patches have been studied in 

 the domestic mammals as well as in man. In man they are 

 from 80 to 100 mm. long and as much as 20 mm. broad ; in 

 the horse they vary in size according to the number of nodules 

 (50-200) ; in cattle and sheep 20 to 50 follicles are found, in the 

 pig 24 to 30 small groups, in the dog 1 5 to 30, and in the cat 4 

 to 7 patches. 4 



The large intestine derives its name from its greater pro- 

 portions as compared with the small intestine. This may be 

 observed even in the short terminal intestine of the fishes, 

 apart from the sphincter which in many of the fishes divides 



1 A.. Oppel, loc. cit., partii., p. 326. 2 Ellenberger, loc. cit., p. 695. 



3 Ibid., p. 698. *Ibid., p. 698. 



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