140 Facts Compelling Us to Reject Preformation 
processes which are essentially identical with each other, 
but has been thereby driven to an attempt at explanation, 
which is wholly artificial and indefensible. 
In order to make the artificiality of his interpretation 
of the most difficult cases clearer, let us consider further 
the following examples. 
It is known that regeneration is not usually an exact 
repetition of the ontogenetic process. 
“Until the last few years,” writes Delage, “it has been 
regarded as a dogma that regeneration is a repetition of 
ontogeny. That is that the regenerating organ or limb 
goes through the successive stages of development 
through which it went in its first formation. Yet the 
question has not been thoroughly enough investigated to 
permit the statement that it always does this, and in many 
cases it is certain that it does not proceed in this way. 
Thus a round tailed salamander regenerated a round tail 
from the first and not the flattened finlike tail of the larva, 
the crab regenerates an adult foot and not a foot like that 
of its larva, Zoaea, The limb or organ regenerated after 
a wound arrives at once at the stage which corresponds to 
the age at which regeneration takes place.” 114 
Further, regenerations of ectodermic tissues at the 
expense of entodermal or mesodermal tissues are not 
rare. We have already seen how the crystalline lens, 
embryologically of ectodermic origin, regenerates in the 
triton from the mesodermic iris. The anterior intestine 
of Tubifex rivulorum, whose ontogenetic origin is 
ectodermal, regenerates, with the exception of a small 
portion at the end, from entodermal tissues.15 
Delage: L’hérédité etc. P. 104—105. 
45H. Haase: Uber Regenerationsvorginge bei Tubifex rivulorum 
Lam. mit besonderer Beriicksichtigung des Darmkanals und Ner- 
