299 
of the European Ornis, and its Causes. 
and that of the subspecies one hundred and forty times, as great 
as with those ornithologists who form their opinions in accord¬ 
ance with strict zoological notions. 
Reichenbach and Brehm assert that the notion of the species 
is subjective : whoever requires a more convincing proof, over¬ 
leaps the bounds of discretion. 
Strictly speaking, the only objectively distinct forms presented 
by nature are the individuals. All further conceptions are sub¬ 
jective views—separations on account of differences observed or 
supposed to be observed. These differences belong objectively 
to animals; their estimation and relative valuation is exclusively 
a subjective affair. It is a matter of subjective choice whether 
we separate the Ostrich-like birds from the other birds as a 
distinct class, or unite them with them; it is a matter of sub¬ 
jective choice whether we separate the Herons as an order from 
the other Grallse, and the Ducks from the other Natatores, or 
place them together; it is a matter of subjective choice whether 
we leave the Linnean genera Falco and Strix in their original 
condition, or break them up into many genera, and so forth. 
Lastly, it is a matter of subjective choice whether we separate 
individuals as species, which only differ from each other by a 
different state of plumage or a different coloration,—e. g. Hali - 
aetus leucoryphus , Pall, {unicolor, Gray), and H. macei, Temm., 
or Larus heinei, Horn., and L. canus, L., or AEgialites homeyeri, 
Br., and AS. hiaticula, L.; one of them may be converted into 
the other in time. It is a matter of subjective choice whether 
or no we separate Charadrius pardela, Pall., from C. hypome - 
lanus, Pall. In the case of living animals we need only wait a 
few months to see how, in the same individual, the one bird 
becomes converted into the other. It is a matter of subjective 
choice to separate Alauda semitorquata, Br., from A. tartarica, 
Pall., as the one form agrees exactly with the female of the 
other. In the above-mentioned cases I believe it is possible to 
come to a perfectly concordant view, although at present this 
does not exist throughout. Nature presents conditions which 
may bring about a common conception; but she also presents 
objective differences, which in separate individuals have, in fact, 
caused the young, or the female, or the winter dress to be re- 
x 2 
