igo THEORETICAL BIOLOGY 



assumption that they belong to the organogeny of lower 

 animals, which have branched off at an earlier date. It will 

 never be possible to prove that the organs of the higher 

 animals can be formed without these " detours." Who will 

 undertake to show that the so-called rudiments of gill-slits in 

 the Mammalia are not necessary for the development of the 

 organs characteristic of those animals ? 



It is simply grotesque to talk of remnants from past ages, 

 of vestigial organs, or of embryonic degeneration (coeno- 

 genesis). 



All such ideas originate from making a quite uncritical 

 assumption of an analogy with the centripetal architecture 

 of human implements, and then applying it to the centrifugal 

 architecture of organisms. 



Yet one thing more. The child is never created from the 

 mature organs of its parents. Rather, the child, since it 

 comes from the same germ-plasm as its parents, travels the 

 same path of genesis as they, in order to develop finally its 

 individual form. This form is not based on a model all ready 

 prepared, but represents the definitive conclusion of a life- 

 process that never before ended up in this particular way. 

 And so it follows that the definitive form of an organism can 

 never harbour within it the vestigial remains of an organ that 

 once upon a time was functional. 



If we insist on looking for a science corresponding to 

 morphology to meet the case of our implements, though their 

 mode of genesis is the very contrary of that of organisms, the 

 science of architectural style might be considered, because 

 even centripetal architecture shows at certain periods certain 

 similarities. Moreover, the science of style does not concern 

 itself with the functions of implements, but only with their 

 mode of genesis. Like morphology, it is based on comparison, 

 and seeks accordingly for signs of genesis and not for signs 

 of function. It investigates homology, not analogy. But 



