LESSON 64.] NUTRITION IN MAN. 219 



959. In the CIRRIPEDS the same condition obtains. 



960. The CRUSTACEA mark a higher advance, by the possession 

 of a large, well-developed liver, in addition to an intestine and two 

 apertures. 



961. The INSECTS are truly remarkable for the great perfection 

 which their organization displays. Provided with mouths exquisitely 

 adapted to their varied food, the structure of their internal organs is 

 quite complicated. 



962. Here we meet, not only with salivary glands, but frequently 

 existing to the extent of three pairs of them as many pairs as man 

 Jhimself possesses, and endowed, apparently, with similar functions. 

 In addition, they all have a liver, and some of them (Blatta) a pan- 

 creas, whilst the intestinal canal is divisible into nearly as many 

 portions as that of the human subject ; and, finally, many of them 

 possess kidneys. 



963. The higher members of the class ARACHNIDA, the Spiders, 

 have a liver and a kidney. 



964. In the MOLLUSCA we find no advance, but in many of its 

 members a falling off of development. 



965. In the TUNICATA, the only accessory organ is a liver. The 

 like in the BRACHIOPODA and LAMELLIBRANCHIATA. In the G-ASTERO- 

 PODA, salivary glands are added. 



966. The CEPHALOPODS, like many Insects, have a plurality of 

 stomachs, but no positive advancement is discernible ; as a whole, 

 the class Mollusca appears to be below the Articulata in general or 

 ganization. 



967. The FISHES, as the lowest class of the Vertebrate sub-king- 

 dom, exhibit only a rudimentary condition of the nutrimental organs ; 

 a liver, however, is always found, and usually well developed ; the 

 salivary glands, for the most part, merge into the pancreatic folli- 

 cles so abundantly developed in the majority of them. 



968. The KEPTILES, as a class, indicate a higher rank ; the sto- 

 mach is always well formed, particularly as regards the internal 

 structure of it ; neither are the accessories of a well-defined nutri- 

 mental function wanting. Although the Frogs are destitute of 

 salivary glands, the three pairs common to the higher animals are 

 distributed amongst the other members of the class. They are all 

 supplied with a liver, have the intestinal canal of sufficient length 

 and. properly divided, and possess kidneys. 



969. The BIRDS, amongst their remarkable developments, pos- 

 sess, many of them, four pairs of salivary glands. Without jaws, 



