HYATT. — ORGANIC CYCLES. 215 



Perliai^s 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 researches upon the meaning and correlations of the 

 epembryonic stages. These were referred 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 



etats analogues a ceux que pre'sentent les especes fossiles dans leur succession ; ou 

 en d'autres teriiies enfin, que le de'veloppement d' une classe dans 1' liistoire de la 

 terre offre, a divers o'gards la plus grande analogie avec le de'veloppement d'un 

 individu aux differentes e'poques de sa vie. La demonstration de cette ve'rite' est 

 un dcs plus beaux rc'sultats de la pak'ontologie raoderne." 



These quotations antedate Louis Agassiz's direct statements since in liis " Dis- 

 cours sur la Succession et le De'veloppement des Etres organises a la Surface du 

 Globe Terrestre," etc., Neuchatel, 1841, he does not give any embryological laws. 

 It is of course quite possible that he did not consider it necessary to mention these 

 in his " Discours,'' which, notwithstanding its title, was merely a general statement 

 of the paleontological evidences of a plan in nature, and ended with an argument 

 for tlie existence of an intelligent creator. Whether this was an omission, or that 

 he did not at that time recognize the importance of the law of palingenesis, does not 

 appear from the text of his publications. The first definite statement under Louis 

 Agassiz's own hand appears to be in his " Recherches sur les Poissons Fossiles," 

 Neuchatel, 1833-43, Vol. I. Chap. IV. p. 93 : — 



" J'aurai par conse'quent souvent recours a I'embryologie d'une part pour recher- 

 cher les analogies entre le squelette des embryons et celui des poissons cartilagineux 

 par rapport aux poissons osseux ; d'autre part pour cclaircir les rapports qui ex- 

 istent entre les formes primitives que nous trouvons chez les poissons des anciennes 

 couches de la terre, et celles qui se voient dans les premiers temps de la formation 

 de I'embryon." 



Tins was certainly written subsequently to the "Poissons d'Eau Douce," since 

 Agassiz quotes Vogt upon tlie following pages 94, 95. He also speaks of the same 

 on page 169, referring both to zoological rank and occurrence in time. 



These are extracts from the Introduction, which was probably written and pub- 

 lished in 1843, judging by tlie immediately following Preface to the first volume, 

 which is dated 1843. 



Vogt's candid admission in his Preface of constant consultations with his master, 

 and his failure to state this law as his own discovery or to claim the authorship 

 subsequently, lead one to think that it might not have originated with him. 



Vogt fully understood the meaning and application of this law, and restates it 

 clearly in his "Zoologische Briefe," Frankfurt am Main, 1851, p. 16, and also in his 

 "Lehrbuch der Geologic und Petrefactenkunde," 1854, Vol. I. p. 471, and tries to 

 apply it to the classification of different groups of the animal kingdom and to tlie 

 history of their fossil remains in " Paleontologische Entwickelung," pp. 423-541. 

 He seems to have been tlie first to have seen its true meaning as a law of evolution, 

 since he completely rejects the doctrine of special creations. It may be that the 

 only way out of this difficulty is to call this Agassiz and Vogt's law, just as it is 

 now not infrequent to speak of Darwin's and Wallace's laws of natural selection. 



