[123] Driesch, Organ. Regul. 1901.
[124] The “ideal whole” is also proved to exist, if any given “Anlage,” say of a branch, is forced to give origin to a root, as has really been observed in certain plants. This case, like many other less extreme cases of what might be called “compensatory heterotypy,” are best to be understood by the aid of the concept of “prospective potency.” It is very misleading to speak of a metamorphosis here. I fully agree with Krašan about this question. See also page [112], note [48], and my Organ. Regul. pp. 77, 78.
[125] Winkler has discovered the important fact, that the adventitious buds formed upon leaves may originate either from one single cell of the epidermis or from several cells together; a result that is very important with respect to the problem of the distribution of “potencies.”
[126] The “regeneration” of the brain of annelids for instance is far better regarded as an adventitious formation than as regeneration proper: nothing indeed goes on here at the locality of the wound; a new brain is formed out of the ectoderm at a certain distance from it.
[127] A full “analytical theory of regeneration” has been developed elsewhere (Organ. Regul. p. 44, etc.). I can only mention here that many different problems have to be studied by such a theory. The formation of the “Anlage” out of the body and the differentiation of it into the completely formed results of regeneration are two of them. The former embraces the question about the potencies not only of the regenerating body but of the elements of the Anlage also; the latter has to deal with the specific order of the single acts of regenerative processes.
[128] And, of course, at the root of every new starting of certain parts of morphogenesis also, as in regeneration and in adventitious budding; these processes, as we know, being also founded upon “complex-equipotential systems,” which have had their “genesis.”
[129] New edition in the “Klassiker d. exakt. Wiss.” Leipzig, Engelmann; see also Bateson, Mendel’s Principles of Heredity, Cambridge, 1902.
[130] For the sake of simplicity I shall not deal here with those cases of hybridisation in which one quality is “recessive,” the other “dominant,” but only allude to the cases, less numerous though they be, where a real mixture of maternal and paternal qualities occurs.
[131] This hypothesis was first suggested by Sutton and is at present held by orthodox Mendelians; but probably things are a little more complicated in reality, as seems to be shown by some facts in the behaviour of so-called “extracted recessives.” In Morgan’s Experimental Zoology, New York, 1907, a full account of the whole matter is given.
[132] Arch. Entw. Mech. 21, 22, and 24, 1906–7; see also Doncaster, Phil. Trans. Royal Soc. London, B. 196, 1903. The influence of different temperature upon the organisation of the hybrids is not always quite pure, inasmuch as the paternal and the maternal forms may themselves be changed by this agent. In spite of that there exists an influence of the temperature upon the hybrid as such, at least with regard to certain features of its organisation.