GEGENBAUR: GENEALOGICAL STANDPOINT 265 



Gegenbaur's morphological system was out-and-out 

 evolutionary. " The most important part of the business 

 of comparative anatomy," in Gegenbaur's eyes, " is to find 

 indications of genetic connection in the organisation of the 

 animal body " (Elements, p. 67). 



The most important clue to discovering this genetic 

 connection is of course that given by homology ; it is indeed 

 the main principle of evolutionary morphology that what is 

 common in organisation is due to common descent, what 

 is divergent is due to adaptation. " Homology . . . corre- 

 sponds to the hypothetical genetic relationship. In the 

 more or the less clear homology, we have the expres- 

 sion of the more or less intimate degree of relationship. 

 Blood - relationship becomes dubious exactly in propor- 

 tion as the proof of homologies is uncertain " (Elements, 



P- 6 3 ). _ 



It is worth noting that while Gegenbaur agrees with 

 Haeckel generally that morphological relationships are 

 really genealogical, that, for instance, each phylum has 

 its ancestral form, he enters a caution against too hastily 

 assuming the existence of a genetic relation between two 

 forms on the basis of the comparison of one or two organs. 

 " In treating comparative anatomy from the genealogical 

 standpoint required by the evolution-theory," he writes, "we 

 have to take into consideration the fact that the connections 

 can almost never be discovered in the real genealogically 

 related objects, for we have almost always to do with the 

 divergent members of an evolutionary series. We derive, 

 for instance, the circulatory system of insects from that of 

 Crustacea . . . but there exists neither a form that leads 

 directly from Crustacea to insects nor any organisatory state 

 (Organisationszustand}, which as such shows the transition. 

 Even when one point of organisation can be denoted as 

 transitional, numerous other points prevent us from regarding 

 the whole organism strictly in the same light " (Grundsiige, 

 p. 75). The real ancestral forms cannot, as a rule, be dis- 

 covered among living species, nor often as extinct. " When 

 we arrange allied forms in series by means of comparison, 

 and seek to derive the more complex from the simpler, we 

 recognise in the lower and simpler forms only similarities 



