84 



FACTS AND FANCIES 



and toes of man, which appear to descend to us 

 unchanged from the amphibians or batrachians 

 of the Carboniferous period. In this ancient 

 age of the earth's geological history, feet with 

 five toes appear in numerous species of rep- 

 tilians of various grades (Fig. 2). They are 

 preceded by no other vertebrates than fishes, 

 and these have numerous fin-rays instead of 

 toes. There are no properly transitional forms 

 either fossil or recent. ♦How were the five-fin- ., 

 gered limbs acquired in this abr ;pt way ? Why 

 were they five rather than any other number ? 

 Why, when once introduced, have they cr 'tinued . 

 unchanged up to the "present day? Haeckel's 

 answer is a curious example of his method: v 

 " The great significance of the five digits de- 

 pends on the fact that this number has been 

 transmitted from the Amphibia to all higher 

 vertebrates. It would be impossible to dis- 

 cover any reason why in the lowest Amphibia, 

 aj well as in reptiles and in higher vertebrates 

 up to man, there should always originally be 

 five digits on each of the anterior and posterior 

 limbs, if we denied that heredity trom a com- 

 mon five-fingered parent-form is the efficient 

 cause of this phenomenon ; heredity can alone 

 account for it. In many Amphibia certainly, as 



