32 IMMUNITY IN HEALTH 



appear in genera so widely separated that quite inde- 

 pendent though similar origins must be assumed. 



The different types of junction of the small and large 

 intestines. 



Type A. — The junction of the large and small intes- 

 tines may be hardly apparent, or may be indicated 

 only by a change of calibre, an external constriction 

 or an internal valve. 

 Most fishes. 

 Most amphibians, 

 Most reptiles, 



A few birds, e.g., the Parrot, 



Some carnivorous marsupials, e.g., the Tasmanian 

 Devil (Dasyurus Viverinus or Sarcophilus Satan- 

 icus), 

 Some edentata, e.g., the Three-toed Sloth (Bradypus 



Tridactylus), 

 The Laughing Jackass of Australia (Dacelo), 

 Most Whales, 

 Bears, 

 Bats, 

 Weasels. 



Type B. — In addition to demarcation of the junction, 

 the proximal part of the large intestine is dilated, 

 chiefly by a bulging of the antimesenterial border, to 

 form a single pouch or caecum. 



This single caecum is of small size in : — • 



A few fishes, e.g., the Dogfish (Scyllium Canicula), 

 Some reptiles, e.g., the Indian Python, 

 A very few birds, e.g., the Heron, 

 Some monotremes, e.g., the Platypus (Orintho- 

 rhynchus), 

 Many carnivorous mammals, e.g., Cat (Felis Domes- 



tica), and Dog (Canis Familiaris), 

 Man. 

 The single caecum tends to be larger in ; — 



