PRIMITIVE MAN. 853 



products of creation. Every species is more or less 

 rariable, and this variability may be developed by 

 different causes. Individuals exposed to unfavourable 

 conditions will be stunted and depauperated; those 

 in more favourable circumstances may be improved 

 and enlarged. Important changes may thus take 

 place without transgressing the limits of the species, 

 or preventing a return to its typical forms ; and the 

 practice of confounding these more limited changes 

 with the wider structural and physiological differences 

 which separate true species is much to be deprecated. 

 Animals which pass through metamorphoses, or which, 

 are developed through the instrumentality of inter- 

 mediate forms or " nurses/' * are not only liable to 

 be separated by mistake into distinct species, but they 

 may, tinder certain circumstances, attain to a premature 

 maturity, or may be fixed for a time or permanently 

 in an immature condition. Further, species, like in- 

 dividuals, probably have their infancy, maturity, 

 and decay in geological time, and may present 

 differences in these several stagos. It is the remainder 

 of true . specific types left after all these sources of 

 error are removed, that creation has to account for; 

 and to arrive at this remainder, and to ascertain its 

 nature and amount, will require a vast expenditure 

 of skilful and conscientious labour. 



3. Since animals and plants have been introduced 

 upon our earth in long succession throughout geologic 



* Mr. Mungo Ponton, in his book " The Beginning," has 

 based a theory of derivation on this peculiarity. 



