1. 



■>Atn 



I 



flif, 



e. 



"ee in ij^ 



^DC^t a 



aC» 



nianj 



ftiions of 

 iA animal 



of tlies 



of Cu-ll 



•_rn Terr 



1 specif- 

 remote 



01 



iiii;' 



JerU' 



re- 



t¥ 



iriDg 



her 

 the ^ 



of 



only"; 







u 



il 



Ch. XXX VII.]' 



ALTEENATE GENEEATIOX. 



327 



manufacture of new races, and a want of time since tlieir 

 orio'in to brin<^ about the extinction of the varieties which 

 still link togetlier the divergent members of th^ series^ and 

 lie remarks tliat the species of these polymorphous genera 

 are nnusuallj variable. When the reader has reflected 



on what will be said in 



XLII 



ule 



many missing links, and why ^ protean genera 



are 



the exception. No cine to this enigma is afforded by the 

 hypothesis of special creation. On the other hand, if it had 

 been found that fertile hybrids could sprinir from animals 



emote 



currence of protean genera might certainly be explained; but 

 in that case they ought to have been universal, and the 



animal 



my 



Alternate generation. — The discovery in certain classes of 

 invertebrate animals of what has been called ^alternate 



generation,' has 



suggested to 



some zoologists 



a possible 



mode by which nature may usher abruptly into the world 

 not only new^ organisms but even types of being of a higher 

 grade than any which pre-existed in the same class. Certain 

 sertularian polyps give birth to other polyps like themselves, 



same 



and structure, and this maj continue for many generations 

 till at last one of the series gives birth to a more highly 



Formerly naturalists 



Medusa 



Medus 



even family, of decidedly higher 

 sation than the Sertulariae. 



mor 



If then it is said, under a 

 change of conditions the Sertularia and the Medusa should 

 each of them go on for an indefinite number of generations 

 producing, according to the more ordinary rules of inherit- 

 ance, offspring like themselves, we should have an example of 

 the coming into existence of a new and higher form without 

 the disappearance of the lower one from which it had been 

 evolved ; but, unfortunately for such speculations, nothing 

 of the kind has ever been witnessed. The Sertularia, although 

 it is hatched from a,n po-o- nAvav r^r-^ri.-.r.^c, ^^^ T...4- ^4 — ^i,. 



A* 



