I02 PHYSIOLOGY OF THE INVERTEBRATA. 



animal and vegetable substances. These contain albuminoids, 

 fatty and starchy matters, and earthy salts. The food is torn 

 to pieces by means of the chelae. The wide and short oeso- 

 phagus leads into a large globular stomach containing chi- 

 tinous teeth, the object of these teeth being to sub- divide 

 the food so that it may be acted upon by the digestive fluid 

 poured into the intestine. The only lateral appendage of the 

 alimentary canal of Carmius is the so-called liver. It is an 

 organ of considerable size, and consists of two symmetrical 

 halves. Its secretion has the following reactions : — 



It decomposes fats and oils with the formation of glycerol 

 and fatty acids. It converts starch into dextrose, and dis- 

 solves albumin. The action of the secretion upon milk is to 

 render it transparent. The secretion contains leucin and 

 tyrosin, no doubt produced by the metamorphoses of certain 

 albuminous substances. In the words of Prof. M. Foster, 

 F.R.S.,* " one result of the action of the pancreatic juice is 

 the formation of considerable quantities of leucin and 

 tyrosin." These organic compounds are not formed in a liver, 

 for they are " dehydrated in a true liver, forming a series 

 of cyauhydrins or cyanalcohols attached to a benzene nucleus, 

 which then pass into the circulation." 



The principal mineral ingredient found in the ashes (incin- 

 erated at a low temperature) of the so-called liver of Carcinns 

 was sodium carbonate. In the ash of a Vertebrate liver the 

 chief mineral constituents are potassium and phosphoric acid. 



The soluble ferment is readily extracted by the Witticli- 

 Kistiakowsky method, or by the method recently introduced 

 by Dr. N. Kravkoff.f This method consists in precipitating 

 the soluble ferments and albuminoids by means of ammonium 

 sulphate. By treatment with alcohol, the albuminoids become 

 insoluble, and the ferments are then extracted with water. 

 The ferment so extracted converts fibrin into leucin and 

 tyrosin ; as well as liydrolyzes starch. 



* Text-hoolc of Physiology, (4th ed.), 43S. 



t Journal of Russian Chemical Society, 1887, p. 387. 



