SPECIES AND THEIR ORIGIN 



313 



brates they soon close over. Numerous other such 

 vestiges might be cited. The vermiform appendix 

 is a now useless or even dangerous legacy from some 

 herbivorous ancestor. Another useless relic of the 

 ancestral past is the muscular equipment of the 

 human ear, sometimes so com- 

 plete (or so well innervated) that 

 their possessor has a quite un- 

 human capacity for moving that 

 organ. Indeed, some one hun- 

 dred and eighty vestigial organs 

 have been recorded in man (Wie- 

 dersheim). In plants, likewise, 

 are to be found many such sur- 

 vivals. Thus in the Cycads, 

 belonging to the most primitive 

 group of the seed-plants, the 

 sperm-cell is provided with cilia 

 like those of an alga, which are, 

 however, useless, since zygosis 

 does not take place in the water. 

 Vestigial structures, such as have 

 been just described, were likened 

 by Darwin "to the unsounded letters in many 

 words, such as the ' o ' in leopard, the ' b ' in 

 doubt, and the * g ' in reign, which are quite 

 functionless, but tell us something of the past his- 

 tory of the word." l 



The Origin of Species. Granting that new species 

 have come or are now coming into existence, by some 



1 Quoted from Thomson and Geddes' " Evolution." 



FIG. 114. Two cil- 

 iated sperms of Cycas 

 revoluta just previous to 

 their breaking away from 

 each other to swim in the 

 watery secretion of the 

 pollen tube. -- (After 

 Miyake.) 



