398 TEE ZOOLOGIST. 



In a homogeneous crowd of people we are attracted by their 

 little differences, taking their really important agreements for granted ; 

 in a compound crowd we at once sort the people according to their 

 really unimportant resemblances. That is human nature. 



The terms " convergence " and " parallelism " are convenient if 

 taken with a generous pinch of salt. Some authors hold that these 

 terms are but imperfect similes, because two originally different 

 organs can never converge into one identical point, still less can their 

 owners whose acquired resemblance depresses the balance of all their 

 other characters. For instance, no lizard can become a snake, in 

 spite of ever so many additional snake-like acqusitions, each of which 

 finds a parallel, an analogy in the snakes. Some zoologists therefore 

 prefer contrasting only parallelism and divergence. A few examples 

 may illustrate the justification of the three terms. If out of ten very 

 similar black-haired people only two become white by the usual pro- 

 cess, while the others retain their colour, then these two diverge 

 from the rest ; but they do not, by the acquisition of the same new 

 feature, become more alike each other than they were before. Only 

 with reference to the rest do they seem to liken as they pass from 

 black through grey to white, our mental process being biased by the 

 more and more emphasized difference from the majority. 



10 Ax Bx Cx D E F 

 9 

 8 

 7 

 6 

 5 

 4 

 3 



2 Ax Bx 

 1 A B C D E F 



Supposing A and B both acquire the character X and this con- 

 tinues through the next ten generations, while in the descendants of 

 C the same character is invented in the tenth generation, and whilst 

 the descendants of D, E, F still remain unaltered. Then we should be 

 strongly inclined, not only to " key together " C~ with A^L and BJ^, 

 but take this case for one of convergence, although it is really one of 

 parallelism. If it did not sound so contradictory, it might be called 

 parallel divergence. The inventors diverge from the majority in the 

 same direction : Isotely. 



Third case. — Ten people, contemporaries, are alike but for the 

 black or red hair. Black A turns white and Bed E turns white, not 

 through exactly identical stages, since E will pass through a reddish 

 grey tinge. But the result is that A and E become actually more 

 like each other than they were before. They converge, although they 

 have gone in for exactly the same divergence with reference to the 

 majority. 



In all three cases the variations begin by divergence from the 

 majority, but we can well imagine that all the members of a homo- 



