new notes at the end of the common song; and these brand new notes were unmistakably imitated from other species. I heard the first of these two abnormal songs near Chalk Peak, in the Santa
Lucia Mountains, Monterey County, California, June 22, 1919. Over and over
again the bird sang the typical "bouncing" song of the species, plus a low
bubbling warble of four Syllables. The warble was so nearly identical with part
of the song of the Western House Wren (Troglodytes aedon parkmani) as to be,
in itself, mistakable for it. The song ran: tip tip tip ip-prrrrr, chreh-chreh-chreh-chreh. This song struck me at the time as a "freak", but I
made a careful record of it, nevertheless, and on my return home filed the record
away.
This "freak" song was given new meaning when, three years later, namely,
on May 2, 1922, I heard, in the Botanical Gardens of the University of California,
the following: tip tip tip ip-prrrrr, chrip-chrip. The added feature
this time was a perfectly good chirp of the Linnet (Carpodacus mexicanus frontalis). The towhee sang this song repeatedly with no deviation except that
occasionally it used a single instead of a double chirp.
The thing that seems to me significant about this business is that these two "off" songs, coming by chance to my attention, and occurring quite independently of each other in point of space and time, should be so remarkably alike in their "offness". I can hardly escape the belief that the observed facts indicate a racial, rather than an individual tendency at work. Chauncey J. Hawkins, discussing the evolution of bird song (1922, p, 53) asserts that "when we turn from the study of individuals to the group of individuals which has assumed the rank of subspecies then divergences are perpetuated." He mentions some typical evolved differences of utterance between subspecies. The theory is that they exist as fixed differences now, because the original tendency to departure from the type was uniformly expressed by the individuals of a group. The freak or exceptional songs "are not perpetuated in the life of the species nor in subspecies. They are lost with the individuals." I am proceeding on the not too unreasonable assumption that my two aberrant Brown Towhees represent a "group." It seems not improbable that, since two individuals with similarly divergent songs have come to my personal attention, there must be others which have not. I base my assumption on the fact that the two songs are like, not in one respect (which might be accidental) but in several respects, which I shall mention presently. This points to something deeper and more lasting than individual eccentricity.
We know that a Brown Towhee hatched say in Humboldt County behaves, looks, and is "like" another Brown Towhee hatched in Monterey County. It is three hundred miles from Cuddeback to Jolon, but the Brown Towhees of each locality are more nearly alike than any two randomly chosen humans of the same race. Why? Because both individuals—though they, nor their parents, never have come in contact—partake of the specific essence of Pipilo crissalis crissalis. Nothing has gone from one to the other, or even from any ancestral Pipilo to them. Yet they are what the ancestral Pipilo is, in size, shape, color, mannerisms. voice. And, since they are alike in these essentials why should they differ in the essential of song-improvement ? "Germ-cells", says Charles Otis Whitman (1919, p. 179), "behave alike in development, not because anything is transmitted to them, but because they represent identical material and constitu-
