The Recapitulation Theory in Biology 7 



Many other instances were given by Meckel, some fantastic 

 and absurd, others still to be found in the text-books on em- 

 bryology. It was this conception that met with the opposition 

 of von Baer, writing in 1828. Von Baer refers to 



"The accepted idea, that the embryo in higher .animals passes 

 through the permanent forms of the lower. . . . This idea, 

 which was born in a time when, besides Malpighi and Wolff, 

 no connected investigations had been undertaken upon the 

 early periods of the embryology of any animal, and was especi- 

 ally carried out by a man who possessed perhaps the most 

 knowledge upon the embryology of the higher organisms, could 

 not help but arouse great support, because it was based upon a 

 multitude of special proofs. . . . Some supporters were so 

 zealous that they spoke no longer of similarity, but of complete 

 identity, and acted as though the correspondence were proven 

 universally and in each particular. We read a short time ago, 

 in a paper upon the blood circulation of the embryo, that the 

 human embryo does not omit a single animal form." 6 



"That," remarks Montgomery, "must indeed have been the 

 luscious Springtime of the theory!" 



Von Baer urged against the prevailing view of recapitulation 



" (1) that no adult animal ever has a yolk sac, or (2) is sur- 

 rounded by embryonic fluids; (3) that it is not the case that an 

 embryo of a higher animal in each embryonic stage corresponds 

 in every point with an adult of a lower species, or (4) that in 

 the ontogeny of a lower form structural relations do not occur 

 which are found in the adult of a higher; (5) that it is equally 

 not the case that parts which are characteristic of only the high- 

 est forms appear latest in the ontogeny." 7 



8. The " Theory of Types." 



Recapitulation in its next phase became intimately involved 

 in that scientific theory of the natural world which preceded 

 the evolutionary or Darwinian conception now current, and 

 which stubbornly contested the claims of the latter until over- 

 whelmed by an incontrovertible array of fact. It is known as 

 the "theory of types," and is associated especially with the 

 names of Georges Cuvier, Louis Agassiz, Johannes Mueller, 

 and Richard Owen. The conception has been analyzed and 

 traced to various sources by Merz in his "History of European 



• Quoted by Montgomery, loc. cit., p. 177. 

 1 1bid. p. 176. 



