24 READINGS IN BIOLOGICAL SCIENCE 



by means of natural selection, from having become injurious to the species 

 under changed habits of life. The process of reduction is probably often 

 aided through the two principles of compensation and economy of growth; 

 but the later stages of reduction, after disuse has done all that can fairly 

 be attributed to it, and when the saving to be effected by the economy of 

 growth would be very small, are difficult to understand. The final and com- 

 plete suppression of a part, already useless and much reduced in size, in 

 which case neither compensation nor economy can come into play, is per- 

 haps intelligible by the aid of the hypothesis of pangenesis. But as the whole 

 subject of rudimentary organs has been discussed and illustrated in my 

 former works, I need here say no more on this head. 



Rudiments of various muscles have been observed in many parts of the 

 human body; and not a few muscles, which are regularly present in some 

 of the lower animals can occasionally be detected in man in a greatly re- 

 duced condition. Every one must have noticed the power which many 

 animals, especially horses, possess of moving or twitching their skin; and 

 this is effected by the pamiiciihis carnosiis. Remnants of this muscle in an 

 efficient state are found in various parts of our bodies; for instance, the 

 muscle on the forehead, by which the eyebrows are raised. 



The extrinsic muscles which serve to move the external ear, and the in- 

 trinsic muscles which move the different parts, are in a rudimentary con- 

 dition in man, and they all belong to the system of the pamiiciihis; they are 

 also variable in development, or at least in function. I have seen one man 

 who could draw the whole ear forwards; other men can draw it upwards; 

 another who could draw it backwards; and from what one of these persons 

 told me, it is probable that most of us, by often touching our ears, and thus 

 directing our attention towards them, could recover some power of move- 

 ment by repeated trials. The power of erecting and directing the shell of 

 the ears to the various points of the compass, is no doubt of the highest serv- 

 ice to many animals, as they thus perceive the direction of danger; but I 

 have never heard on sufficient evidence, of a man who possessed this power, 

 the one which might be of use to him. Some authors, however, suppose that 

 the cartilage of the shell serves to transmit vibrations to the acoustic nerve; 

 but Mr. Toynbee, after collecting all the known evidence on this head, 

 concludes that the external shell is of no distinct use. The ears of the chim- 

 panzee and orang are curiously like those of man, and the proper muscles 

 are likewise but very slightly developed. I am also assured by the keepers 

 in the Zoological Gardens that these animals never move or erect their 

 ears; so that they are in an equally rudimentary condition with those of 

 man, as far as function is concerned. Why these animals, as well as the pro- 

 genitors of man, should have lost the power of erecting their ears, we can- 

 not say. It may be, though I am not satisfied with this view, that owing to 

 their arboreal habits and great strength they were but little exposed to dan- 

 ger, and so during a lengthened period moved their ears but little, and thus 



