Page:Philosophical Review Volume 14.djvu/375

359 &#39;chance&#39; appearance. To the law of identity and to 'elements' no attention is paid.

Into this last scheme, there fit the appearance of the new qualities resulting, e.g., in the synthesis of every chemical compound, and, at the critical point, under definite conditions of temperature and pressure, etc., of every physical state.

In the origin of species by mutation, the reviewer finds what seems to be another case of the same kind. Experiment shows that organisms of the same descent under the same conditions give diverse mutations, and this after a long period of constancy. The factors causing these are accordingly internal. Even if, then, the external conditions for inducing mutations were known, and could be used, it would be impossible to say beforehand what the character of even one mutation would be. But the fact of diversity precludes seemingly the establishing of any empirical law of determination even after one or more mutations have occurred.

There seems to be, therefore, an absolute irregularity here. For we have either many characters coming from one cause (what de Vries calls a 'pangene') in the germ; or else there are as many such causes as there are unit-characters appearing. This last does not do away with the irregularity, but puts it back only one step further; as also is the case, with a difference in number only, if it is claimed that the cause has been long latent. At some point of time, epigenesis, chance, perhaps irregularity are to be admitted, or else 'there is nothing new under the sun.' But there is another set of experimental facts brought out by the work of Driesch, Boveri, Conklin, and Wilson on germinal prelocalization in the egg which bear on this question. These investigators have been able to show that the eggs of a number of species contain localized areas of protoplasm which have a causal connection with the formation of definite parts of the embryo; also that this grouping of stuffs in the egg is gradual; i.e, that at first even it contains few if any of these specific stuffs; that the chromosomes of the nucleus are the bearers of the hereditary characteristics and probably cause this grouping. The nucleus appears to contain an original preformation of elements which correspond each for each to the unit-characters of the coming organism. These cause the cytoplasm to develop epigenetically. Accordingly, for a new unit-character to appear, must not a new cause in the chromosome arise de novo, and is it not therefore very difficult to escape the acceptance of chance or absolute irregularity here? Why should one not accept this, except