KNOWLEDGE OP ANJMAL*S WHOLE HISTORY REQUIRED. 43 



have arisen from some unknown cause at a former period ; from 

 which sprang different breeds or varieties, such as those of our 

 domesticated animals ; and of which the cessation permits the 

 race to return to its original form, as takes place to a certain 

 degree when domesticated animals resume the original habits of 

 their kind. 



21. It will be further necessary, that the Naturalist should 

 know the changes of form, which the animals he is considering 

 may undergo, in the progress of their growth and development ; 

 so as not to separate as distinct species, those which are but dif- 

 ferent stages of the same. And he ought, further, to be ac- 

 quainted with the forms of both sexes ; and with the changes in 

 aspect which they may undergo, from the influence of season, 

 climate, &c. In fact, the whole history of every species of animal 

 ought to be known to the Naturalist, before he begins his 

 arrangement ; and as this is very far from being the case at pre- 

 sent, it is obvious that there is the widest scope for the labours 

 of any amount of observers, and that many corrections will have 

 to be introduced into the arrangements which Naturalists have 

 formed. In fact, these arrangements must be regarded, in many 

 instances, as provisional or temporary ; to be confirmed, or set 

 aside in favour of some other more perfect, by increased know- 

 ledge. 



22. Hence, the greatest encouragement may be offered to 

 those who are commencing the pursuit of Natural History, on 

 however limited a ecale ; for every one, who observes accurately, 

 and (still more) who collects and arranges facts with the guid- 

 ance of sufficient previous knowledge, is rendering a service to 

 Science. Even those who are entirely ignorant of Zoology may 

 do much in this way ; but their chances of error are great ; and 

 they should be careful to record what they actually see, carefully 

 separating from this the inferences or reasonings which they have 

 founded upon it. But those who have some previous knowledge 

 of the Science may do much more ; for they are guided by it how 

 to observe, and what to observe. The pleasure which is derived 

 from a country walk, or from a visit to the sea-coast, is thus 

 enhanced beyond all conception. A very moderate amount of 



