1880. | Editors’ Fable. 727 
ling with the universal phenomenon of “inexact parallelism,” 
which has received satisfactory explanations at various times, 
It is gratifying to find Mr. Agassiz giving a general assent to 
the doctrine of derivation, but we observe that he cannot forbear 
_ intimating that he does not enter the ranks‘of the evolutionists on 
account of the society he finds there. He says in effect,—your 
derivation is probably true, but you can’t tell how it was done, so 
what are you going to do about it?- And he proceeds to show 
that they cannot do anything about it, in the following manner: 
“The time for genealogical trees has passed; its futility can, per- 
haps, best be shown by a simple calculation which will point out 
at a glance what these scientific arboriculturists are attempting. 
Let us take for instance the ten most characteristic features of the 
Echini, The number of possible combinations which can be pro- 
duced from them is so great that it would take no less than twenty 
years, at the rate of one new combination a minute for ten hours 
a day to pass them in review. * * On the other hand, in spite 
of the millions of possible combinations which these ten characters 
, 
mensely short of the possible number. We have not more than 
twenty-three hundred species actually representing for the Echini 
the results of these endless combinations. Is it astonishing there- 
fore that we should fail to discover the sequence of the genera, 
even if the genera, as is so often the case, represent, as it were, 
fixed embryonic stages of some sea-urchin of the present day?” 
Precisely what relation the above considerations bear to the tra- 
cing of the phylogenies, it is difficult to perceive. If Mr. Agassiz 
had insisted that any or all of the millions of possible combinations 
e has pictured may have existed as extinct species, he would in- 
deed have presented us with an inextricable genealogical puzzle. 
But he does not do this, for he admits that the number of the 
forms which have actually existed is limited. Does Mr. Agassiz 
mean that there has been no order in this limitation; that there 
have existed no causes which have rendered some combinations 
possible and others impossible? Such would appear to be the 
Spirit of his proposition, but it is the objection of a mathematician. 
and not that of a practical biologist. The chairman of Section B 
admits that genealogies of single characters may be constructed; 
therefore genealogies of orders, families and genera can be con- 
structed, for they are, or ought to be (for they ultimately must be); 
efined by single characters. Having thus established the lines 
tents of the divisions so defined, is greatly restricted. We can no 
