109 



crusts, which when broken ^transversely proceed on 

 rays from the seam to the centre. This seam I take 

 to have been the habitation of the animal in its poly- 

 pus state, and in which the body was affixed. The 

 animals of the testaceous tribe in general, as they 

 increase in age, increase their shells in thickness, until 

 they have lived their stated time, and that is clone by 

 adding a new crust to, as several, if not all the tubtili, 

 the oysters, and the nautili, witness. i3y length of 

 time they grow inactive and dead, the effect of ex 

 *treme old age suffering other marine bodies, as worms 

 and oysters, to affix themselves to their outer coat. 

 The like appearance we frequently meat with on be- 

 lemnitae, when the animal within was either waxed 

 old or dead. 



One might enlarge upon the analogies which may 

 "be found, between the origin of these minute aninriaie 9 

 the origin of plants, and that of those other animals, 

 which we are more acquainted with. But we shall 

 be better able to judge of those analogies, when we 

 come to know more both of plants and animals. 



The surprising facts which the study of natural his- 

 tory lays before us day by day, may convince us, that 

 the nature of plants and animals, is as yet but very 

 imperfectly known, indeed much more imperfectly, 

 than many have been apt to imagine. All we know 

 is very little, in comparison of what remains un- 

 knovvii. And this consideration, as it should prompt 

 us, still more diligently to enquire after truth, so it 

 should make us exceeding cautious how we jtidge of 

 the nature of things from so few principles as we are 

 at present masters of. 



25. One circumstance more is worthy our obscr- 

 vation ? with regard not only to insects, but in some 

 measure to the whole animal creation, namely the va- 

 rious transformations they undergo. Those kinds of 

 animals Which are viviparous, which produce their 

 young alive, undergo the slightest alteration : yet 

 even these have some. Growth itself is the lowest 



