242 



NA TURE 



[July 



1894 



difficulties come in, and there they meet us in battalions. 

 At the outset, the co-operation of working specialist and 

 practical bibliographer is required ; but viewing the sub- 

 ject from different standpoints, the specialist has his ideas 

 and the bibliographer his, and we are fortunate if we 

 escape the familiar difficulty — qtiot homines, tot scntentia. 

 As to the difficulties of execution, they are, of course, 

 primarily, how the whole system of the sciences should be 

 divided, how far the divisions should be carried, and how 

 the material, the particular items to be entered, should 

 be distributed among them. For it is clear that for so 

 vast a material no mere alphabetical index would suffice. 

 All the contributions to one particular subject must be 

 brought under the eye in one group, not scattered up 

 and down through a thousand pages, according to the 

 mere accident of the words used by the authors in their 

 titles. The mere alphabetical arrangement attracts by its 

 simplicity : but in a work of this extent it would be mis- 

 placed, the entries would be lost, and thee.xhaustive search 

 which would always be required would take longer than 

 the time needed to make one's self acquainted with the 

 scheme of classification adopted, which trouble would only 

 need to be taken once for all. There are, moreover, im- 

 portant collateral advantages attaching to the preparation 

 of practically distinct indexes for the different branches 

 of science. Not to enlarge further on the difficulties of 

 a Subject-catalogue — such as terminology, translation, 

 consultation of originals, itc. — we would only say there 

 is no royal road through all these obstacles. The path 

 through them must always be a thorny one. Neither is 

 there any standard of perfection, nor would it be attain- 

 able if there were. The best that can be expected is a 

 sensible workable compromise. This is attainable, and 

 we have little doubt will ultimately be attained, and so a 

 key furnished to the whole series of contributions lo the 

 growth of every twig and branch of the tree of scientific 

 knowledge from one end of the nineteenth century to the 

 other. Since the inception of their present undertaking, 

 the Royal Society have not ceased to occupy themselves 

 with the question of a parallel Subject-catalogue, nor is 

 it any wonder if the result has so long continued to be 

 only negative. But with each decade the matter becomes 

 more urgent, and to deal with it increased efforts are 

 demanded, and greater sacrifices become justifiable. 

 We believe that the Society are now on the eve of start- 

 ing actual work upon the undertaking, and so commencing 

 another monumental contribution to the " Improvement 

 of Natural Knowledge." 



EPIGENESIS. 

 Gestaltung und Vcrerbung. Eine Entwickeluiigsme- 

 chanik der Organismen. By Dr. Wilhelm Haacke. 

 Pp- 337> with illustrations. (Leipzig: T. O. Weigel 

 Nachfolger, 1893.) 



WHILE it is correct to say that, as a matter of 

 history, epigenesis implies merely the observed 

 fact that the fertilised egg-cell, from which the new 

 organism of each generation arises, is, under the micro- 

 scope, a nucleated mass of protoplasm not differing from 

 other cells, it is not so certain that the simplicity of the 

 historical conception is any help to the problem as it 

 exists for us to-day. For in the growth of an idea as it 

 NO. I 289. VOL. 50] 



passes from mind to mind, there is, at the best, but a 

 formal continuity. Most often the meaning of the word 

 has been so added to, and so taken from, that it becomes 

 like the famous patched coat, which contained none of 

 the original m.aterial. For the present, the question at 

 issue is very different from the problem of those who 

 used the word in earlier times. We know that we must 

 not expect to see under the microscope the character of 

 an elephant or of a mouse stamped upon the protoplasm 

 of the fertilised egg-cell. We wish to know whether the 

 observed facts of development and inheritance can be 

 co-ordinated under the idea that the protoplasm of the 

 fertilised egg-cell is as like the protoplasm of other cells 

 as it seems; or, under the idea of preformation, that 

 each structure of the adult has a structural representa- 

 tive in the egg. But many side issues arise, and identical 

 sets of facts really devoid of bearing upon the main 

 question are brought forward with equal triumph by 

 advocates of either theory. Take an example, not one 

 that, so far as this writer knows, has been employed, but 

 which may serve as a type. The intestine of the higher 

 animals is very much longer than the length of their 

 bodies, and is disposed in coils and loops. Dr. Gadow 

 has shown that this disposition in the case of birds falls 

 into seven or eight well-marked types which ate so con- 

 stant as to have high corroborative value in classi- 

 fication. It may well be that these varieties of twisting 

 and coiling depend upon physical conditions, upon the 

 relations of the growing intestine to the growth anii 

 structure of the surrounding viscera and of the skeletal 

 tissues. Here, the advocate of epigenesis would say, 

 are characters that need no preformation in the egg, that 

 are stamped in due course upon its simple protoplasm. 

 But no preformationist need suppose that the invincible 

 elements in the gerjn are to grow up by their own forrc 

 out of all relation to surrounding conditions. The cen 

 trifugal activities of the egg, if they exist, are there to 

 supply those differences for which there is no cause in 

 the outer world. They supply the factor, the resultants 

 between which and the forces of the outer world show 

 differences under what seem to be identical conditions. 



In Dr. Haacke's book a large number of instances are 

 brought forward in which facts of the organic world seem 

 to be explicable by physical conditions. These are all 

 used as arguments against preformation, and specially 

 against Weismann and, as is the fashion just now, 

 against the generalisations of Darwin. 



Thus, under the name Epimorpliism, he groups together 

 a number of facts that seem to show the existence of 

 grades and lines of development apparently independent 

 of utility. Such are, for instance, the increase of size in 

 organs like horns or, indeed, of whole animals ; increases 

 which in the past history of the earth have apparently 

 actually led lo the destruction of the animals in question. 

 Again, in most groups gradual alterations of form gener- 

 ally leading from regular symmetry to irregular form can 

 be traced. Specific markings, colours and so forth, as 

 Eimer before has showed, in many cases seem to follow in 

 regular sequences independent of utility and adaptation. 

 The degeneration of useless or of unused organs goes on 

 independently of direct advantage to the animals. Geo- 

 graphical distribution, as Dr. Haacke showed in an in- 

 teresting paper, published in 1885, reveals that jfor most 



