One interesting point about the song of crickets is that the number of notes uttered in any given space of time—per minute, say—varies according to the temperature, the two rising together. Professor Dolbeare was the first, as far as I know, to call attention to this fact, and he is thus confirmed by a lady: “One cool evening a cricket was caught and brought into a warm room. In a few minutes it began to chirp nearly twice as rapidly as the out-of-door crickets. Its rate very nearly conformed to the observed rate maintained on other evenings under the same temperature conditions (as now indoors). From this series of observations we found that the rate of chirping was, as Professor Dolbeare says, very closely dependent on the temperature.”[27] So the crickets are little thermometers—sixty-three degrees Fahrenheit to one hundred chirps per minute. As we have seen, the Katydids give concerts, and we may therefore infer that they like their own music in a musically appreciative way; that they listen to each other as critical connoisseurs, whether they have other feelings or not, and that it is not a mere matter of the female alone admiring the sounds made by the male, just because _he_ makes them. In all this, however, the admiration is confined—at least, as far as we know—to one species—that to which the musician belongs. Katydids appreciate the performances of Katydids. But there is one group of performers whose music gives satisfaction, not merely to individuals of other species than their own, but to such as are not even included in the same order with them, so that racial pride or family prejudice cannot be the reason of it. Towards these stars we will now turn our gaze.