270 Studies in the Theory of Descent. 



II. 



CONCLUSIONS FROM PHYLOGENY. 



THE considerations previously set forth are entirely 

 based on Fritz Muller's and Haeckel's view, that 

 the development of the individual presents the 

 ancestral history in mice, the ontogeny being a 

 condensed recapitulation of the phylogeny. 



Although this law is generally true all recent 

 investigations on development having given it 

 fresh confirmation it must not be forgotten that 

 this " recapitulation " is not only considerably 

 abbreviated, but may also be " falsified," so that 

 a searching examination into each particular case 

 is very desirable. 



The question thus arises, in the first place, as 

 to whether the markings of caterpillars, so dis- 

 tinct at the different stages of growth, are actu- 

 ally to be regarded as residual markings inherited 

 from the parent form ; or whether their differences 

 do not depend upon the fact that the caterpillar, 

 in the course of growth, is exposed to different 

 external conditions of life, to which it has adapted 

 itself by assuming a different guise. 



The former is undoubtedly the case. It can 



