WHAT IS EVOLVED IM EVOLUTION? 269 



This Rapid Evolution difficult to Account for by any Working 

 of Natural Selection. — Thus far it is the evolution of morpho- 

 logical characters with which we have been dealing. Genera, 

 or species, arc often spoken of as being evolved. When 

 language is used in this way we mean that there is an or- 

 derly succession of genera. This orderly succession of forms 

 we can readily conceive; but a genus is a group of spe- 

 cies which possesses certain common characters of higher 

 than specific rank. It is one thing to speak of the succes- 

 sion of the different forms and another thing to speak of 

 the attainment by offspring of characters not possessed by 

 ancestors. We are accustomed to the explanation by Dar- 

 win that the method of this attainment of new characters is 

 by the gradual accumulation of varietal characters which are 

 considered as arising spontaneously. Taking the case before 

 us, we can imagine the form of the loop of the Magellania as 

 having been acquired before its calcification ; but the differ- 

 ence between the presence of a calcified loop and its absence 

 was brought about within a brief period (geologically con- 

 sidered), while the modification of the loop, as indicated in 

 the several genera of the Terebratulidae, can be conceived of 

 as having been produced gradually in the geological sense. 

 Thus, when we consider evolution as applying to the produc- 

 tion of differences, great difficulty is found in accounting for 

 the structural differences, which are the basis of our classifica- 

 tion into groups of family and higher rank, by the slow pro- 

 cesses required for the working of natural selection upon nor- 

 mal variations. 



What is Evolved? — Hence, in reply to the question " What 

 is evolved?" it is evident that morphological characters are 

 evolved — not species, genera, or any kind of groups of organ- 

 isms. There is an evolution of the characters of the individual, 

 and because this evolution takes place in many individuals at 

 the same time, we recognize the evolution by the appearance 

 of the modification in the many individuals, and group them 

 into new genera or families, on account of their differences 

 from other forms. 



How Does the Evolution Proceed? — How does the evolution 

 proceed? Not by the ab initio construction of a new organ- 



