6o6 



THE POPULAR SCIENCE MONTHLY. 



be turned inside out without interference with the business of diges- 

 tion. The skin in these cases must have a chemical digestive power, 



> 



,t ?*5*^ : ?&M ' 



Fig. 6. a, Sertularia (Diphasia) pinnata, natural size : a', fragment of the game enlarged, carry- 

 ing a male capsule (a), and showing the hydrothecae (h) ; b. fragment of Campanularia negltcta 

 (after Hincks), showing the polypites contained in their hydrothecae (h), and also the point at 

 which the ccenosarc communicates with the stomach of the polypite (o). 



as the food taken in mass, and frequently living substance, or even 

 whole animals, is dissolved without trituration or mechanical aid. The 



human skin has powers of absorption, 

 and in some slight degree a person may 

 be fed through it. The continuation of 

 the skin which lines the digestive canal 

 is supplied with new powers of secretion ; 

 so that, instead of producing perspira- 

 tions, oils, etc., it manufactures chemicals 

 for changing food. Hence the principle 

 of digestion and the character of the 

 organs are fundamentally the same in 

 all animals, the lowest with the highest. 

 Only in the amoeba, hydra, etc., digestion 

 is accomplished with the least possible 

 expenditure. 



A true stomach must be wholly de- 

 voted to the elaboration of food, leaving 

 other functions to other organs. This 

 requires that it be wholly shut off from 

 other cavities of the body ; and it were 

 better to have two openings, one for re- 



Fis.7. Digestive System of a Beetle Ception of food, the other an outlet for 

 ( Carabus auratus) : a, oesophagus ; b, . n ,i r n 



crop ;c, gizzard ; d, chyiific stomach; waste matter, in order to give tne.tooci a 



e, Malpighian tubes;/, intestine ; a, it.,* j + +1^ ;K,- 



cloaca ; h, supposed renal vessels. single direction and prevent the mingling 



