Sept. 6, 1883] 



NATURE 



45i 



blinded by a superstitious belief in those forms of words which 

 too often pass current as philosophy. 



But if we are content to start with a number of organisms 

 ready made, — a somewhat humiliating start, however, — we still 

 have to a-k, How do these vary so as to give new species? It 

 is a singular illusion in this matter, of men who profess to be 

 believers in natural law, that variation may be boundless, aimless, 

 and fortuitous, and that it is by spontaneous selection from 

 varieties thus produced that development arises. But surely 

 the supposition of mere chance and magic is unworthy of science. 

 Varieties must have causes, and' their causes and their effects 

 must be regulated by some law or laws. Now, it is easy to see 

 that they cannot be caused by a mere innate tendency in the 

 orgai ism itself. Every organism is so nicely equilibrated, that 

 it has no such spontaneous tendency, except within the limits set 

 by its growth and the law of its periodical changes. There may 

 however, be equilibrium moie cr less s'able. 1 believe all 

 attempts hither. o made have failed to account for the fixity of 

 certain, nay, of very many, types throughout geological time ; but 

 the mere considerati m that one may be in a more stable state of 

 equilibrium than another so far explains it. A rockingstone has 

 no more spontaneous tendency to move than an ordinary b«ild"r, 

 but it may be made to move with a touch. So it probably is 

 with organis us. But, if si, then the causes of variation are 

 external, as in many cases we actually know them to be; and 

 they must depend on instability or change in surroundings, and 

 this so arranged as not to be too extreme in amount, and to 

 operate in som determinate direction. O serve how' remarkable 

 the unity of the adjustments involved in such a supposition. How 

 superior they must be to our rude and always more or less 

 un-uccessful attempts to produce and carry forward varieties and 

 races in definite directions ! This cannot be chance. If it 

 exists, it must depend on plans deeply laid in the nature of 

 things, el e it would be most monstrous magic and causeless 

 miracle. Still more certain is this conclusion when we consider 

 the vast and orderly succession made known to us by geology, 

 and which must have been regulated by fixed laws, oidy a few 

 of which are as yet known to us. 



Beyond these general considerations, we have others of a more 

 special character, based on palrcontological facts, which show 

 hov imperfect are our attempts, as ye% to reach the true causes 

 of the introduction of genera and species. 



One is the re nark able fixity of the leading types of livin » 

 beings in gedogical time. If instead of framing, like Haeckel, 

 fanciful phytogenies, we take the trouble, with Barrande an 1 

 Gaudry, to trace the forms of life through the period of their 

 existence, each along its own line, we shall be greatly struck 

 with this, and especially with the continuous existence of many 

 low types of life through vicissitudes of physical conditions of 

 the most stupendous character, and over a lapse of time scarcely 

 conceivable. What is still more remarkable is, that this holds 

 in grou s which, within certain limits, are perhaps the most 

 variable of all. In t'ae present world no creatures are individu- 

 ally more variable than the protozoa ; as, for example, the 

 foraminifera and the sponges. Yet these groups are fun lament- 

 ally the same from the beginning of the palaeozoic until now ; 

 and m>dern species seem scarcely at all to differ from specimens 

 procured from rocks at least half way back to the beginning of 

 our geol 'gical record. If we suppose that the present sponges 

 and foraminifera are the descenlants of those of the Silurian 

 period, we can affirm, th it, in all that vast lap-e of time, they 

 hive, on the whole, made little greater change than that which 

 may be observed in variable forms at present. Thesaue remark 

 applies to other 1 >w animal forms. In forms somewhat higher 

 and less varia'de, this is equally noteworthy. The pattern of 

 the venation of the wings of cockroaches, and the structure and 

 form of Ian 1-snail-, gaily- worms, and decapod crustaceans, were 

 all settled in the Carboniferous age in a way that still remains. 

 So were the foliage and the fructification of club-mosses and 

 ferns. If at any time members of these groups branched off, so 

 as to lay the foundation of new species, this must have been a 

 very rare and exceptional occurrence, and one demanding even 

 some suspension of the ordinary laws of nature. 



Certain recent utterances of eminent scientific men in England 

 and France are most instructive with reference to the difficulties 

 which encompass this subject. Huxley, at present the leader of 

 English evolutionists, in his " Rede Lecture " ' deUvered at 

 Cambridge, England, holds that there are only two "possible 

 alternative hypotheses" as to the origin of species, — (1) that of 

 1 Report in Nature, June 21 (p. 187), corrected by the author. 



"construction," or the mechanical putting-together of the 

 material- and parts of each new species separately ; and (2) that of 

 " evolution," or that one form of life "proceeded from another" 

 by the "estab ishment of small successive differences." After 

 comparing these modes, much to the disadvantage of the first, 

 he concludes with the statement that " this was his ca-e for 

 evolution, which he rested wholly on arguments of the kind he 

 had adduced ; " these arguments being the threadbare false 

 analogy of ordinary reproduction and the tran -formation of 

 species, and the mere succession of forms more or less similar 

 in geological time, neither of them having any bearing whatever 

 on the origin of any species or on the cause of the ob>erved 

 succession. With reference to the two alternatives, while it is 

 true that no certain evidence Ins yet been obtained — either by 

 experiment, observation, or sound induction — a- to the mode of 

 origin of any species, enough is known to show that there are 

 numerous possible methods, gr luped usually under the heads of 

 absolute creation, mediate creation, critical evolution, and gradual 

 evolution. It is also true that almost the only thing we certainly 

 know in the matter is that the differences characteristic of classes, 

 orders, genera, and species, must have arisen, not in one or two, 

 but in many ways. An instructive commentary on the capacity 

 of our age to deal with these great question- is afforded by the 

 fact that this little piece of clever mental gymnastics should have 

 been practised in a university lecture and in presence of an 

 educated audience. It is also deserving of notice, th at, though 

 the lecturer takes the development of the Nautili and their allies 

 as his principal illustration, he evide . tly attaches no weight to 

 the argument in the opposite sen-e deduced by Barrande — the 

 man of all others most profoundly acquainted wi h these animals 

 — from the palaeozoic cephalopods. 



Another example is afforded by a lecture recently delivered 

 at the ko>al Institution in London by Professor Flower. 1 The 

 subject i- "The Whales, Past and Present, a d their Probable 

 Origin." The latter point, as is well known, Gaudry had 

 candidly given up. "We have questioned," he says, "these 

 strange and gigantic sovereigns of the tertiary ocean- as to their 

 ancestors, — they leave us without reply." Flower is bold enough 

 to face this problem ; and he does so in a fair ad vigorous way, 

 though limiting himself to the supposition of slow and gradual 

 change. He gives up at once, as every anatomist must, the idea 

 of an origin from fishes or reptiles. He thinks the a ic slcrs of 

 the whales mu-t have been quadrupedal mamma's. He is obliged 

 for good reasons to reject the ;eals and the otters, and turns to 

 th ■ ungulates, though here, also, the difhcul ies are formidable. 

 Finally he has recourse t > an imaginary ancestor, supposed to 

 have haunted marshes and rivers of the mesozoic age, and to 

 have been intermediate between a hippopotamus and a dolphin, 

 and omnivo'ous in diet. As this animal is altogether unknown 

 to geology or zoology, and not much less difficult to account for 

 than the whales themselves, he very properly add-, "Please to 

 recollect, however, that this is a mere speculation." He trusts, 

 however, that such speculations are "not without th-ir use" ; 

 but this will depend .upon whether or not they lead men's minds 

 from the path of legitimate science into the quicksands of 

 baseless conjecture. 



Gaudry, in his recent work, " Enchainements du Monde 

 Animal, "- though a str »n r advocate of evolution, is obliged in 

 his final resume to say, " II ne laisse point percer le mystere qui 

 entoure le develoopement primitif des grandes clas-es du monde 

 animal. Nul homme ne sait comment ont e e former les premiers 

 indtvidus de foraminiferes, de polypes, o'etoiles de mer, de 

 crinoides, &c. Les fossiles primaires ne nous ont pas encore 

 fourni de preuves positives du passage des animaux d'une classe 

 a ceux d'une autre clase." 



Professor Williamson of Manchester, in an address delivered 

 in February last before the Royal Institution of Great Britain, 

 after showing that the conifers, ferns, and lycipods of the palaeo- 

 zoic have no known ancestry, use; the significant word;, "The 

 time has not yet arrived for the appointment of a botanical king- 

 at-arms and constructor of pedigrees." 



Another caution which a palseontol 'gist las occa ion to give 

 with regard to theories of life has reference to the tendency of 

 biologists to infer that animals and plants were introduced under 

 embryonic forms, and at first in few and imperfect species. 

 Facts do not substantiate this. The first appearance of leading 

 types of life is rarely embryonic. On the contrary, they o' ten 

 appear in highly perfect and specialised for ns ; often, howev r, 

 of composite type, and expressing characters afterwards so 

 1 Reported in Nature. - Paris, 1883. 



