244 ELEMENTS OF SCIENCE 



see, and the habits and food of which differ widely from 

 those of the parent since its larval condition. We 

 cannot think, however, that the insect possesses any 

 recollection of that condition so that its parental actions 

 are guided thereby. 



As we said in the beginning of the chapter, organisms 

 have definite relations (i) to time ; (2) to space; and (3) 

 to one another. 



As to time, it is widely known that some animals have 

 become extinct. Thus the wolf has disappeared from 

 England since the days of Henry VIII., while the 

 bustard has ceased to exist, although eighty years ago it 

 wandered over the South Downs and Salisbury Plain. 

 Similarly, plants once common in certain places have 

 since vanished, as the many peculiar plants of St. Helena 

 have been almost entirely destroyed by the rabbits and 

 goats introduced into that island. 



The evidences we possess of past organic life is afforded 

 us by the five kinds of fossils before described.* This 

 record is an exceedingly imperfect one, remains of 

 animals and plants having been only here and there 

 exceptionally preserved by some favouring accidents, 

 and often in a very fragmentary manner. The study of 

 these organic remains constitutes the science of 

 Palaeontology, and we must refer our readers to treatises 

 on that science for further information. Here we will 

 only say that in the primary rocks have been found 

 many remains of echinoderms, molluscs, arthropods and 

 fishes. 



In the secondary strata we find evidences that great 

 numbers of huge reptiles existed, some grazing or feed- 

 ing on trees, and others of most predacious habits. 



* See ante, p. 170. 



