The mistake, I think, is not in stating that the two processes are sometimes similar, or even identical, but in stating the matter as though the regenerative process repeats the embryonic method of development. If the same conditions prevail, then the same factors that bring about the embryonic development may be active in bringing about the regenerative processes. In fact, we should expect them to coincide oftener than appears to be the case, but this may be due to the conditions being different in the young and in the adult. It has been claimed also that in some cases there is regenerated a structure like that possessed by the ancestors of the animal. The stock example of this process is Fritz Müller’s result on the regeneration of the claw of a shrimp, _Atypoida protimirum_.[105] Fraisse and Weismann and others have brought forward this case as demonstrative. The animal is said to regenerate a claw different from any of those in the typical form, and one that resembles the claw of another related genus, _Carodina_. The value of evidence of this sort is not above question. Przibram has shown in other crustacea that when a maxilliped is cut off a structure different in kind often regenerates, but that after several months the typical structure returns. Do we find here an ancestral organ that first appears, and then gives way to its more modern representative? If it _resembled_ the maxilliped of any other crustacean, the evidence would, no doubt, be accepted by those who accept the evidence furnished by Müller. What then shall we say to the case, first discovered by Herbst, in which the eye of certain prawns being cut off, an antenna-like organ regenerates? Since these antennæ are similar to those possessed by the same animal, shall we assume that it once had antennæ in place of eyes? Another comparison, that Fraisse has made, is worth quoting as showing how far credulity may be carried. In the regeneration of the tail of certain lizards pigment first appears in the ectoderm of the new part and then sinks deeper into the layers. Fraisse found a lizard on Capri in which the tail is pigmented throughout life, and although he did not know whether or not the pigment is in the skin he suggests that this lizard represents an ancestral condition, that is repeated by the regenerating tails of other forms.