. A text-book of comparative physiology [microform] : for students and practitioners of comparative (veterinary) medicine. Physiology, Comparative; Veterinary physiology; Physiologie comparée; Physiologie vétérinaire. 600 COMPARATIVE pitch. quaUty, and intensity, some species croaking so as to be heard at the distance of at least a mUe. It is a matter of easy observation that when frogs cioak the capacity of the mouth cavity is greatly increased, owing to the distention of resonat- ing sacs situated at each angle of the jaws. When tree-frogs croak, thei* throats are greatly disten
. A text-book of comparative physiology [microform] : for students and practitioners of comparative (veterinary) medicine. Physiology, Comparative; Veterinary physiology; Physiologie comparée; Physiologie vétérinaire. 600 COMPARATIVE pitch. quaUty, and intensity, some species croaking so as to be heard at the distance of at least a mUe. It is a matter of easy observation that when frogs cioak the capacity of the mouth cavity is greatly increased, owing to the distention of resonat- ing sacs situated at each angle of the jaws. When tree-frogs croak, thei* throats are greatly distended, apparently m suc- cessive waves. W BPBOIAIi OOM8IDBIU,TXONB AMD SUBOSART. I Svolntioa.—The very lowest forms, and in fact most inverte- brate groups, seem' to be voiceless. Darwin has shown that voice is, in a large number of groups, confined either entirely to the male, or that it is so much more developed in hrai as to become what he terms a " sexual ; There is abundant evidence that males are chosen as mates by the females, among birds especially, not alone for superiority in beauty of plumage, but also for their song. Thus, by a process of natural selection (sexual selection), the voice would tend to improve with the lapse of time, if we admit heredity, which is an undeniable fact, even among men—whole families for generations, as the Bachs, having been musicians. One can also understand why on these principles voice should be especially developed in certain groups (birds), while among others (mammals) form and strength should determine sexual selection, the strongest winning in the contests for the possession of the females, and so propagating tiieur species under tiie more favorable cireumstanoe of choice of tiie most desira- ble females. , , .1. 1 . Pathology teaches that, when certain parts of the brain (speech-centers) of man are injured by accident or disease Je poww of speech may be lost From this it is evident ttiat the vocal apparatu
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Keywords: ., bookauthormillswes, bookcentury1800, bookdecade1890, bookyear1890
