70 



THE AMERICAN NATURALIST [Vol. LI 



researches on the elimination of organs in a series of dif- 

 ferent plants. 



The critical value of these different investigations is 

 not in every case equal. Some are distinctly fragmentary, 

 and in others the differences between eliminated and sur- 

 viving are so small as to be of extremely doubtful sig- 

 nificance. If one examines critically the actual biometric 

 constants in the more extended of these studies (e. g., 

 Crampton's and Bumpus's as analyzed by Harris^ ^) he 

 can not but be impressed with the doubtfulness of many 

 of the differences. However, if we take all these re- 

 searches at their face value, and give all the benefit of the 

 doubt to the weak, then they agree in indicating that the 

 survivors are of somewhat different type physically than 

 the eliminated. 



But nearly as many investigations have been made 

 which show that, on the whole, the survivors are not 

 physically different from those naturally eliminated. 

 Again the studies of Weldon^^ on Claiisilia come first. 

 Closely related to these is di Cesnola's^^ work on Helix. 

 All three of these investigations agree in showing no sig- 

 nificant difference in physical type between the general 

 population before elimination and the selected survivors 

 from that population after elimination. There was in 

 TTrlix and in Clausilia lam 'mat a some reduction in vari- 

 ability, but even that failed in another species of Clau- 

 silia. Kellogg and BelP^ were not able to find any evi- 

 dence that survivors and eliminated were different in 

 respect of either type or variability under natural con- 

 ditions, in the case of boos, or of the lady-bird beetle Hip- 

 podamia. Ponrl.^^ in a much moiv cxtorided series of ob- 

 servations than tbo?;e of Davoni)m-t. f..nn<l no i-olation 

 between tlio colors of cliickons and tlicir elimination l)y 



Vol. [ir. ].p. 290-307, 1904. 



(Vsnol.i. A. P., Biometril-a, Vol. V, pp. 'A^7-?m. lf>07. 

 1- Kolloirff, v.. and Bell, R. G., Proc. Wa,^Mnr,fon Acml. Sri., Vol. Vr, pp. 



203-.^;{2, 1004. 



"Pearl, R., Amer. Nat., Vol. XLV, pp. 107-117, 1911. 



