ABORTIVE ORGANS, 59 
tiation which causes the resemblance of the higher in- 
complete, to the lower complete forms. To limit our- 
selves to one example: it is quite incomprehensible 
why the ear-bones of the mammal should be developed, 
by the circuitous process of the formation of germinal 
fissures, if it were a mere questian of histological and 
morphological differentiation. This explanation fails 
also with regard to the whole class of the phenomena 
of purposeless and abortive organs, and, finally, the 
“evoluticnary type” itself as it rules the groups and 
regulates individual development, still remains without 
an explanation, 
