And after sundry illustrations and qualifications, he concludes (p. 200):-- "Hence every detail of structure in every living creature (making some little allowance for the direct action of physical conditions) may be viewed either as having been of special use to some ancestral form, or as being now of special use to the descendants of this form--either directly, or indirectly, through the complex laws of growth." But it is one thing to say, Darwinically, that every detail observed in an animal's structure is of use to it, or has been of use to its ancestors; and quite another to affirm, teleologically, that every detail of an animal's structure has been created for its benefit. On the former hypothesis, for example, the teeth of the foetal 'Balaena' have a meaning; on the latter, none. So far as we are aware, there is not a phrase in the 'Origin of Species', inconsistent with Professor Kolliker's position, that "varieties arise irrespectively of the notion of purpose, or of utility, according to general laws of Nature, and may be either useful, or hurtful, or indifferent." On the contrary, Mr. Darwin writes (Summary of Chap. V.):-- "Our ignorance of the laws of variation is profound. Not in one case out of a hundred can we pretend to assign any reason why this or that part varies more or less from the same part in the parents...The external conditions of life, as climate and food, etc., seem to have induced some slight modifications. Habit, in producing constitutional differences, and use, in strengthening, and disuse, in weakening and diminishing organs, seem to have been more potent in their effects." And finally, as if to prevent all possible misconception, Mr. Darwin concludes his Chapter on Variation with these pregnant words:-- "Whatever the cause may be of each slight difference in the offspring from their parents--and a cause for each must exist--it is the steady accumulation, through natural selection of such differences, when beneficial to the individual, that gives rise to all the more important modifications of structure which the innumerable beings on the face of the earth are enabled to struggle with each other, and the best adapted to survive." We have dwelt at length upon this subject, because of its great general importance, and because we believe that Professor Kolliker's criticisms on this head are based upon a misapprehension of Mr. Darwin's views--substantially they appear to us to coincide with his own. The other objections which Professor Kolliker enumerates and discusses are the following*:--([Footnote] *Space will not allow us to give Professor Kolliker's arguments in detail; our readers will find a full and accurate version of them in the 'Reader' for August 13th and 20th, 1864.) "1. No transitional forms between existing species are known; and known varieties, whether selected or spontaneous, never go so far as to establish new species."