BIOLOGICAL INVESTIGATIONS. 141 



of selected primitive forms were not homologous with the uni- 

 cellular bodies of the simplest Protozoa. 



I say selected, meaning thereby that an ovum taken at hap- 

 hazard anywhere throughout the animal kingdom would be as 

 likely to confuse the observer striving to solve the question of 

 the origin of metazoanal structures as to throw light upon this 

 problem. If the students of comparative ontogeny are correct, 

 an organism taken from among the primitive forms of any 

 genetic series has within itself a record of historical value pro- 

 portioned to its place in its own genetic line and also to the 

 position of its genetic stock in the whole animal kingdom, and 

 its evidence may be, and practically is, dependent upon its grade 

 or position. If it lie near the genetic base of origin, it contains 

 a more complete record, and recapitulates more ancestral char- 

 acters than if it is drawn from the acmatic period of the phy- 

 logeny ; and finally, if it come from the other extreme of the 

 phylogeny, where animals are passing through retrogressive 

 phases, its ontogeny may be so deficient as to fail to recapitu- 

 late, as in the case of the young of man, the hitherto essential 

 characters of the forms from which it was evolved. 



This is the result of a law of development of the ontogeny, 

 which Cope during his life was in the habit of demonstrating 

 and using among recent animals, and the lecturer among fossils. 

 It is particularly well shown in such complete series as may be 

 found in the living Batrachia and in fossil Cephalopoda, and has 

 been independently discovered by several observers. 1 



1 The following seems to the author a fair statement of the history of this law. 

 Haeckel, in his Morphologic der Organismen, vol. ii, 1866, p. 1S4, gave, under the 

 title of " Gesetz der abgekiirsten oder vereinfachten Vererbung," what seemed to 

 me for some years to be a definition of this law, but in writing my Bioplastology 

 I came to the conclusion (p. 78) that this was merely an emended general statement 

 of the law of correlation between the ontogeny and phylogeny. An abbreviated 

 statement of the literature seems to be as follows : Hyatt, " Parallelism between 

 Stages of Life of the Individual and Group of Tetrabranchiata," Mem. Bost. Soc. 

 Nat. Hist., vol. i, Pt. II, read Feb. 21, 1866, published 1867 (see Rep. of Custodian 

 of B. S. N. H., May i, 1867, and May, 1868) ; Cope, "Origin of Genera," read 

 October, 1868, published 1869 (see Account of Cope's Origin of the Fittest, p. vi, 

 Preface) ; Wiirtenburger, op. cit., p. 28, Leipzig, iSSo ; Buckman, op. cit., vol. for 

 1891, p. 290, also " Some Laws of Heredity and Their Application to Man," Proc. 

 Cotteswold Nat. Club, vol. x, Pt. Ill, 1891-92, p. 258 ; Ganong, W. F., " Contr. 

 Morph. and Ecol. of the Cactacae," read before Society for Plant Morphology and 



