66 THE DESCENT OF MAN 



assign any reason. Mr. Wood, after describing numerous 

 variations, makes the following pregnant remark: "Notable 

 departures from the ordinary type of the muscular structures 

 run in grooves or directions, which must be taken to indicate 

 some unknown factor, of much importance to a comprehen- 

 sive knowledge of general and scientific anatomy." " 



That this unknown factor is reversion to a former state 

 of existence may~be admitted as in the highest degree prob- 

 able." It is quite incredible that a man should through 

 mere accident abnormally resemble certain apes in no less 

 than seven of his muscles, if there had been no genetic con- 

 nection between them. On the other hand, if man is de- 

 scended from some apelike creature, no valid reason can 

 be assigned why certain muscles should not suddenly reap- 

 pear after an interval of many thousand generations; in the 

 same manner as, with horses, asses and mules, dark-colored 

 stripes suddenly reappear on the legs and shoulders, after 

 an interval of hundreds, or more probably of thousands, 

 of generations. 



These various cases of reversion are so closely related to 

 those of rudimentary organs given in the first chapter, that 



^^ The Rev. Dr. Haughton, after giving ("Proc. E. Irish Academy," June 

 21, 1864, p. 715) a remarkable case of variation in the human flexor poUicis 

 longus, adds: "This remarkable example shows that man may sometimes 

 possess the arrangement of tendons of thumb and fingers characteristic of the 

 macaque ; but whether such a case should be regarded as a macaque passing 

 upward into a man, or a man passing downward into a macaque, or as a con- 

 genital freak of nature, I cannot undertake to say. ' ' It is satisfactory to hear 

 so capable an anatomist, and so imbittered an opponent of evolutionism, admit- 

 ting even the possibility of either of his first propositions. Prof. Macahster has 

 also described ("Proc. E. Irish Acad.," vol. x., 1864, p. 138) variations in the 

 flexor poUicis longus, remarkable from their relations to the same muscle in 

 the Quadrumana. 



" Since the first edition of this book appeared, Mr. Wood has published 

 another memoir in the "Phil. Transactions," 1870, p. 83, on the varieties of 

 the muscles of the human neck, shoulder and chest. He here shows how ex- 

 tremely variable these muscles are, and how often and how closely the varia- 

 tions resemble the normal muscles of the lower animals. He sums up by re- 

 marking: "It will be enough for my purpose if I have succeeded in showing 

 the more important forms which, when occurring as varieties in the human sub- 

 ject, tend to exhibit in a sufficiently marked manner what may be considered as 

 proofs and examples of the Darwinian principle of reversion, or law of inheri- 

 tance, in this department of anatomical science." 



