jAiTOAEY 29, 1897.] 



8GIENGE. 



165 



. Perhaps, in consequence of pressure of 

 •other work or of his theoretical views, 

 Louis Agassiz seemed to have lost sight of 

 the great importance of continuing his re- 

 searches upon the meaning and correlations 

 of the epembryonic stages. These were re- 

 ferred to in his publications, but were not 

 made as prominent as they deserved after 

 the lectures at the Lowell Institute in 1849, 

 and in his personal talks with his students 

 or in his lectures I cannot remember that 

 they were ever treated directly by anything 

 more, than incidental references, although 

 ■embryology was very often the principal 

 theme. 



Nevertheless, I must have got directly 

 •from him, subsequently to 1858, the princi- 

 ples of this branch of research, and through 

 this and the abundant materials furnished 

 ■by the collections he had purchased and 

 placed so freely at my disposal, I soon be- 

 gan to find that the correlations of the 

 •epembryonic stages and their use in study- 

 ing the natural affinities of animals was 

 practically an infinite field for work and 

 •discovery. 



Although within a year after the begin- 

 ning of my life as a student under Louis 

 Agassiz I had become an evolutionist, this 

 theoretical change of position altered in no 

 essential way the conceptions I had at first 

 received from him, nor the use we both 

 made of them in classifying and arranging 

 forms. This experience demonstrated to 

 my mind the absurdity of disputing the 

 claims of any author to the discovery of a 

 series of facts and their correlations because 

 of his misinterpretation of their more re- 

 mote relations or general meaning. It is of 

 some importance to notice this because it is 

 the rule now to attribute von Baer's and 

 his predecessors' and Louis Agassiz's dis- 

 •coveries in this line to Haeckel. This emi- 

 nent author has, indeed, given one of the 

 most modern definitions of this law and has 

 named it the ' law of biogenesis.' Haeckel's 



discoveries in embryology are sufSciently 

 great without swelling the list with false 

 entries, but it will probably be a long time 

 before naturalists realize and acknowledge 

 this error. Some of the most eminent em- 

 bryologists in this country have adopted the 

 Haeckelian nomenclature without suflicient. 

 critical examination of the term under dis- 

 cussion. The so-called Haeckelian (' law of 

 biogenesis ') is really Agassiz's law of em- 

 bryological recapitulation restated- in the 

 terms of evolution. 



It has surprised me that serious objec- 

 tions to the use of the word ' biogenesis ' in 

 this connection have not been made. This 

 word has been long employed in another 

 sense as antithetical to ' abiogenesis.' The 

 latter has been for many years applied to 

 the theory of the generation of living from 

 inorganic matter, and the former to the 

 theory asserting that living matter can 

 originate only from living matter ; the use 

 of the phrase ' the law of biogenesis ' is 

 consequently inappropriate, since neither 

 did Agassiz's nor Haeckel's discoveries 

 cover so much ground. The former gave 

 us a law for the correlations of the earlier 

 stages of ontogeny with phylogeny. This 

 cannot be called ' the law of biogenesis,' 

 since that has been long ago stated as the 

 law of the origin and continuity of organism, 

 or in other words, the genesis and continu- 

 ity of life from and through living matter 

 only. There are two different manifesta- 

 tions of Agassiz's law, which Haeckel de- 

 fined and named ' palingenesis ' and ' conoe- 

 genesis,' the former referring to the ordinary 

 as regular mode in which the characteristics 

 of ancestors are repeated in the develop- 

 ment of the individual and the other to 

 what is frequently called the abbreviated 

 mode, etc. 



These two modes are by no means all, 

 but at present only the first or simplest 

 manifestations of the phenomena need be 

 treated of. This, or what Haeckel very 



