DIGESTIVE SYSTEM OF THE LOBSTER 173 



filter between the cardiac and pyloric portions. Food thus 

 passed through is distributed in the various diverticula of the 

 hepato-pancreas, where the bulk of digestion takes place. Here 

 also are the absorbing cells which take up the digested foods and 

 turn them over to the blood (Jordan). The end gut or intes- 

 tine plays no role either in digestion or in absorption. The 

 absorption cells have the same general structure as those of the 

 earthworm. The connective tissue in which the hepato-pan- 

 creas is embedded is richly supplied with blood vessels and 

 lymph spaces, which probably receive digested food directly 

 from the absorption cells. 



The digestive fluid which comes from the hepato-pancreas is 

 very complex. It is of yellowish-brown color, not viscous, is 

 rich in albumen, contains a free alkali, and gives a flocculent 

 precipitate with acids. This precipitate, filtered and washed, 

 gives all of the reactions of a globulin. The digestive ferments 

 contained in this juice are (i) a protease or proteolytic ferment 

 similar to the protein digestive ferments of the earthworm and 

 other invertebrates; (2) a lipase or fat emulsifying ferment; (3) 

 an amylase or starch converting ferment. In other allied 

 forms of Crustacea, still more ferments have been obtained from 

 the digestive juices, and these may be present in the lobster. 

 Thus a cellulose dissolving ferment (cytase) was discovered by 

 Biedermann and Moritz from the crayfish. 



The digestive tract of the lobster thus shows a considerable 

 advance over that of the earthworm or other lower types. The 

 functional digestive part is removed from the main tract, but is 

 derived from it as an outgrowth or diverticulum. It represents 

 a step toward still higher types of development, where secretions 

 from different glands are poured into a digestive sac or stomach 

 and intestine. Here in the lobster, the digestive gland still acts 

 as a part of the glandular tube of a worm ; the food is contained 

 in it, and digestion and absorption take place in it instead of in 

 the main digestive tube. In higher animals, all of the glands 

 pour their digestive fluids into the main tube. 



The Blood Vascular System. In the lobster and other forms 

 of arthropods, all of the blood of the organism passes sooner or 



