368 SHIP WORM. 



newly excluded from the egg 5 but it grows to the length of four or 

 six inches, and sometimes more. 



When the bottom of a vessel, or any piece of wood which is con- 

 stantly under water, is inhabited by these worms, it is full of small 

 holes ; but no damage appears till the outer parts are cut away : then 

 their shelly habitations come to view ; in which there is a large space 

 for inclosing the animal, and surrounding it with water. There is 

 evident care in these creatures never to injure one another's habita- 

 tions, by which means each case or shell is preserved entire ; and in 

 such pieces of wood as have been found eaten by them into a sort 

 of honeycomb, there is seen no passage or communication between 

 any two of the shells, though the woody matter between them often 

 is not thicker than a piece of writing-paper. They penetrate some 

 kinds of wood more easily than otaers. They make their way most 

 quickly into fir and alder, and grow to the greatest size. In the 

 oak they make little progress, and appear small and feeble, and 

 their shells much discoloured. 



Since each of these animals is lodged in a solitary cell, and has 

 no access to those of its own species, it has been matter of surprise 

 how they should increase to so vast a multitude. Upon dissecting 

 them, it appears that every individual has the parts of both sexes, 

 and is therefore supposed to propagate by itself. 



The sea-worms, which are pernicious to our shipping, appear to 

 have the same office allotted to them in the waters which the ter- 

 mites have on the land. They will appear, on a very little conside- 

 ration, to be most important beings in the great chain of creation; and 

 pleasing demonstrations of that infinitely wise and gracious Power 

 which formed, and still preserves, the whole in such wonderful order 

 and beauty ; for if it were not for the rapacity of these and similar 

 animals, tropical rivers, and indeed the ocean itself, would be choked 

 with the bodies of trees which are annually carried down by the ra- 

 pid torrents, as many of them would last for ages ; and probably 

 be productive of evils, of which, happily, we cannot in the present 

 harmonious state of things form any idea ; whereas now,' being con. 

 sumed by these animals, they are more easily broken in pieces by 

 the waves ; and the fragments which are not devoured become spe- 

 cifically lighter, and are consequently more readily and more effec- 

 tually thrown on shore ; where the sun, wind, insects, and various 

 other instruments, speedily promote their entire dissolution. 





