222 METAMOKPHOSES OF MAN 



sufficiently rendered — foresaw all the results of this 

 fact considered apart, but he could go no farther. 

 The external differences between this mode of gene- 

 ration and that of the Aphides were too great to admit 

 even of a supposition of any analogy between the two 

 phenomena. 



The splendid works of Saars, Siebold, Loewen, Daly ell, 

 and finally of Steenstrup, by filling up the gap and 

 forming a connecting link, alone permitted the latter 

 to grasp relations, which till then had been imper- 

 ceptible. Still, he must have had a gifted and 

 synthetical mind to arrive at the result. Whatever 

 may be said of the other doctrines of the Danish 

 naturalist, this work will always be regarded as of the 

 greatest value, and as marking an entirely new era in 

 the history of the development of animals. 



The very title of this work shows that the author 

 considered the subject from the same point of view as 

 Chamisso, and that he had been struck especially with 

 the alternation of forms presented by the various 

 generations produced in geneagenesis. This is incon- 

 testably proved by the very first passages in the book ; 

 but Steenstrup did not stop there. He pointed out 

 clearly the physiological fact which characterizes the 

 commencement and termination of the series of gene- 

 rations. This fact is, the reappearance not only of 

 the primary form, but of all the anatomical and 

 physiological characters also, especially of the repro- 

 duction by ova in the usual manner. This conclusion, 

 which was at first drawn from a very small series of 

 facts, has been confirmed by all subsequent researches. 

 It is one of the most important truths Steenstrup has 

 established, and one of his greatest triumphs. 



