MERRIAM — SPECIES AND GENERA 
9 
that it would serve a more useful purpose if the terms species and subspecies 
were so used as to indicate degree of difference, rather than the author’s opinion 
ns to the existence or non-existence of intergrades In my judg- 
ment, forms which differ only slightly should rank as subspecies even if known 
not to intergrade, while forms which differ in definite, constant and easily recog- 
nized characters should rank as species even if known to intergrade. — Science, 
NS, V, pp. 753-758, May 14, 1897. 
If the absence of intergrades in the hands of the student is the rule 
rather than the exception when dealing with mainland forms of 'pre- 
sumably continuous distribution, what shall we say of closely related 
insular forms where the existence of intergrades is an obvious physical 
impossibility? And yet we all know that it is common practice — a 
practice in which I fully concur — to treat such forms as subspecies. 
Does not this demonstrate the absurdity of the intergradation rule? 
On the other hand, by adopting the criterion of degree of divergence, 
the imagination is not overtaxed, erroneous reference of subspecies to 
species from which they were not derived are rendered harmless, and 
the conclusions arrived at — usually the same as by the intergrade 
rule — may be stated without qualms of conscience. 
To certain devotees of this rule, the discovery of intermediate forms 
seems to produce a psychologic shock, upsetting the judgment to 
such a degree that forms obviously entitled to recognition as full species 
are immediately degraded to the rank of subspecies. 
The same is true of genera, for on the discovery of intermediate 
species, certain students feel impelled to bring together, under a single 
generic name, the members of two completely differentiated and easily 
recognizable genera. 
And it may be added parenthetically that the same distorted point 
of view crops out here and there in the remote field of anthropology, 
some authors of distinction bringing together in a single linguistic 
family two or more strongly marked and perfectly distinct families 
because of the discovery (real or imagined) of an exceedingly remote 
ancestral relationship ! 
In these days of the universal acceptance of evolution, is it not 
bard to reconcile such reductions of groups with the facts that must 
be apparent to every one, for if species and genera and linguistic fami- 
lies are to be set aside because of the discovery of intermediate forms, 
does it not follow that sooner or later our classification is doomed to 
destruction, chaos taking the place of system? 
