THE TAPE-WORMS, OR T-ffiNIiE. 52I 



upper part of it, where there is the greatest abund- 

 ance of chyle, which seems to be their natural food. 



In structure they are very simple ; for, being in- 

 tended to be nourished by already digested food, 

 they are not provided with complicated organs of 

 digestion. 



Their body is flat, and composed of numerous 

 articulations; and the head has four orifices for 

 suction a little below the mouth, which is terminal, 

 and continued by a short tube into two ventral 

 canals. The mouth is generally crowned with a 

 double series of retractile hooks or holders. 



We are not to suppose that these worms are 

 created for the purpose of producing disease in the 

 animals they inhabit, but rather that nature has di- 

 rected that no situation should be vacant, where the 

 work of multiplying the species of living beings 

 could be carried on. By thus allowing them to 

 exist within each other the sphere of increase is 

 considerably enlarged. There is, however, little 

 doubt that worms, and more especially those of the 

 present tribe, do sometimes produce diseases in the 

 bodies they inhabit : but we are at the same time 

 very certain that worms do exist abundantly in 

 many animals without at all disturbing their func- 

 tions, or annoying them in the slightest degree : 

 and we ought to consider all these creatures rather 

 as the concomitants than the causes of disease. 



The species of Tamia? are not confined singly to 

 particular animals: men arc subject to several dif- 

 ferent species, and even the people of particular 

 countries and climates are subject to particular 



