Mar., 1916 
THE NEW MUSEUM OF COMPARATIVE OOLOGY 
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anyone should ever have attempted to classify birds on the strength of variation 
in any single set of characters, whether of feather arrangement (pterylosis), 
feather structure, arrangement of muscles, or even of the bony structure itself. 
Position in any scheme of classification, that is, relationship and phylogenetic 
history, is determined by the sum of characters ; and determination of the value 
of any one factor in development involves a knowledge of the rate of change. 
Certain strongly marked characters may have been so recently, that is, so rap- 
idly, acquired as to be almost valueless in determining the deeper, truer, his- 
torical relationship. Other characters, apparently no more distinctive, may yet 
really be so deep-seated, so little subject to change, as to yield conclusive testi- 
mony as to eousinships in the hoary eld. Now it appears that in the complex of 
evolved characters which go to make up a bird, although subject itself to a high 
variation, no single element is more stable, more conservative, more phylogenet- 
ieally eloquent, than that of the egg. No single character of the egg, viewed 
externally, is negligible. Size, color, shape, texture, surface, number even, — all 
are eloquent of relationship and history. Save in the order Passeres, where 
the tendency to vary, long latent or suppressed in the egg, has burst into sudden 
and highly complicated efflorescence, a comparison of egg-shells is exceedingly 
instructive. This does not mean that comparative oology is a substitute for com- 
parative myology, or comparative osteology, or even pterylosis ; but it does 
mean that the egg has its own testimony to offer, and that it is able to throw 
a powerful side light upon history, and so upon the scheme of classification. 
So important is this claim that I pause to note a few instances. The class- 
ical example is that of the Laro-Limicolae. The older science, content with 
appearances, and deceived by homoplasy (that is, the concurrence of forms 
superficially similar, issuing from diverse stocks, which have been acted upon 
by uniform conditions), had, in a sort of childish helplessness, ranged the Gulls 
and Terns alongside the Albatrosses and Petrels. Whereas a glance into any egg 
cabinet shows that the heavily-colored eggs of the Gulls and of the Shore-birds 
are so similar as, in so far forth, to proclaim unity of origin in the parents; 
while the single white egg of the Tube-nosed bird is at the farthest remove of an 
entirely different line of development. The oologist could have told (and did 
tell) at a glance what the older ornithology failed to discover. In like manner, 
the close relationship between the Herons and the Cormorants, testified now by 
the anatomist, but difficult of comprehension on the part of the casual observer 
because of the birds’ very dissimilar appearance, finds instant confirmation in 
the drawer of the oologist. Eggs of the Black-crowned Night Heron could be 
palmed off for those of Baird ’s Cormorant, and vice versa. To take but a single 
instance of a claim to which the anatomist has not yet consented: The oologist 
knows that the heavily-colored egg of a Loon represents age-long differentiation 
from the primitive Uncolored type exhibited by a Grebe’s egg. The separation 
between Loons and Grebes is a very ancient one; yet the anatomist, deceived 
again by homoplasy, and underestimating his own data of diverse osteological 
characters, allows the two groups, Gaviidae and Podicipedidae, to subsist in a 
single order, Pygopodes. 
That such facts are significant, there can be no question. They have by no 
means escaped notice ; but they have not had a sufficient or an exhaustive con- 
sideration. The Museum of Comparative Oology proposes for its first task the 
assembling of such abundant and representative material as will enable Science 
to work out these problems with some degree of intelligence. 
