308 



Nor would I create the impression that the einbryologists and zoolo- 

 gists have utterly deserted the paleontologists in their support of the re- 

 capitulation theory. Several recent papers give considerable aid and com- 

 fort to those of us who still believe in recapitulation. I shall introduce 

 here the conclusions of three of these workers, more particularly because 

 it will afford me an opportunity to correct what I hold to be another error 

 of those who oppose the theory. 



One of the most interesting pieces of evidence that has recently been 

 adduced in favor of the idea that ontogeny recapitulates phylogeny is to 

 be found in a paper by Griggs on "Juvenile Kelps" (28). It is not my 

 purpose, however, to discuss the very interesting evidence which he has 

 recorded, but rather to quote his remarks on the views of His and Morgan, 

 and his general conclusions. His maintains that the reason why ontogeny 

 seems to recapitulate phylogeny is because the stages in development are. 

 as Griggs paraphrases it, "only the physiologically necessary steps for the 

 formation of the adult body from its earliest stage, which in most cases 

 is the egg." With the ideas of Morgan as expressed in his valuable book 

 on "Evolution and Adaptation" we are all familiar. He holds that or- 

 ganisms repeat in their development, not adult stages, but only embryonic 

 stages of their ancestors. To this idea he has given the name of "repe- 

 tition." 



On this point of the recapitulation of embryonic conditions Griggs 

 makes the following pertinent statements : "In the toothless animals, the 

 whale and the bird, the development of teeth in the jaws is entirely un- 

 necessary * * * it may even be said to hinder the attainment of the 

 adult condition. The same is true of the mammalian gill slits and of 

 most structures which have in the past attracted attention in connection 

 with the recapitulation theory. As the ancestral period when such struc- 

 tures were fully developed in the adult becomes more and more remote, 

 the tendency to inherit them becomes less and less, because of the cumu- 

 lative impulses given to the heritage by the nearer ancestors. Conse- 

 quently they are successively less and less developed. Any gradual' loss 

 of inheritance can, in the nature of the case, take place only from the 

 mature condition backward toward the beginning of the life cycle ; other- 

 wise we should have adult structures with no ontogenetic history. There- 

 fore we can understand why it is that in many cases only the embryonic 

 stages of ancestral history persist in the ontogeny." In a foot note he 

 says : "The cutting off of end stages in the development of organs has 



