326 JXgcftible and indigeflible Matters. [Book IX. 



be diffolved fo foon as the other parts are converted 

 into chyle and carried into the duodenum : or from 

 the ftomach being fo much difordered as to digeft im- 

 perfectly. This diforder of the ftomach fometimes 

 proceeds fo far, that the food pafTes through the body 

 almoft unchanged. ' Jn fome cafes food has been re- 

 tained on the ftomach for twenty^four hours, and thrown 

 up without being altered in the leaft. 



The effential oils of animals and vegetables are 

 indigeftible ? they are foluble, however, either in the 

 gaftric juice or the chyle, by which means they be- 

 come medicinal from their ftimulant powers. The 

 eflential oils of vegetables, but more particularly 

 thofe of animals, feem to pervade the very fubftance 

 of the animals whofe food contains much of them. 

 Thus fea birds, which feed on fifh, tafte very ftrongly 

 of them, and thofe which live on that food only 

 during certain times of the year, as the wild duck, 

 -have that tafte only at certain feafons. Two ducks 

 were fed, one with barley, the ether with fprats 

 for about a month, and killed both at the fame 

 time ; when drefled, that fed on fprats was hardly 

 eatable. 



Animals eat lefs in proportion as their food is more 

 nutritious. Thus carnivorous animals require much 

 lefs food than the granivorous, and thefe, than the 

 graminivorous ; animals, indeed, of the laft kind, em- 

 ploy almoft the whole of their time in eating. A 

 correfponding relation is alfo obferved with refpect to 

 the digeftive organs in thefe feveral races of animals ; 

 Carnivorous animals have only one ftomach, grani- 

 vorous animals very generally two, and graminivorous 

 animals four ftomachs, with a greater length of in- 

 teftines. From which circumftances it may be col- 

 lected 



