32 GLANDS FOR PRODUCING SOLVENT FLUIDS. 



the maintenance of the life of the new being tinder 

 the greatly altered conditions of existence. 



49. Glands for producing solvent fluids. — In this 

 digestive tube or cavity the undissolved food must be 

 acted upon, so that it may be dissolved in water. The 

 solution thus prepared is to be taken up or absorbed 

 by the blood. Various secreting glands are therefore 

 developed in connection with the digestive tube. 

 These select certain materials from the blood com- 

 mon to the whole body, and convert them into 

 fluids having very special and peculiar properties 

 and endowments, which when fully iormed pass 

 away from the gland, being conducted by a tube 

 or duct to different parts of the canal, where they 

 become mixed with the food and exert their peculiar 

 influence. Such are the salivary glands of the mouth, 

 the stomach glands, the ratestinal glands, the liver, the 

 pancreas, and several others connected with the in- 

 testine which need not be particularised now — each 

 taking part in a particular but very different ope- 

 ration. The saliva has the property of changing 

 starch into sugar, and in a few seconds. The gastric 

 juice dissolves meat and all forms of fibrin and co- 

 agulated albumen. The pancreas and the liver have 

 to do with the digestion of fatty matter, and the 

 secretions of the intestinal glands exert yet different 

 actions. From the digestive tube nutrient matter is 

 taken up by masses of bioplasm, and by these passed 

 on, as it were, to blood-vessels, as has been already 

 stated in § 40. The newly introduced pabulum is 

 converted into blood by bioplasm, and this blood is 

 driven through the minute vessels (capillaries) in 

 every part of the body. Through the walls of the 

 capillaries, fluid transudes, which is taken up by the 

 bioplasm of the several tissues lying outside the vas- 

 cular canals. In a similar manner it is probable that 

 the bioplasm in the walls of the vessels and the bio- 

 plasm in the blood take up the matters resulting 



