Page images
PDF
EPUB
[ocr errors]

erroneous.

[ocr errors][ocr errors][ocr errors]

individuals take place through the action of the uniformity of the great Laws of Nature, believe that
environment, he will not admit that these changes evolution is due to an infinite number of happy
are inherited ! Yet he believes in changes in breeds accidents? We know of a law which answers all
of domestic animals through “selection.” How can those requirements of simplicity and uniformity of a
selection act, if there is no inherent force to initiate great Law of Nature, which is in harmony with all
the change? If individual peculiarities are inherited, the apparently complicated phenomena of life, which
then it is quite natural that a pointer puppy should solves problems otherwise insoluble, the Law of the
point; but if they are not, why should he not Action of the Environment upon Irritable Proto-
accidentally vary in some other direction? There l plasm. And we are asked to set it aside as non-
must be some internal force rendering variation existent, and believe in innumerable accidental
possible, or the breeder might select for ever without variations, as an efficient substitute !
producing any effect. Practically, in every-day life Mr. Wallace refers, with high approval, to Professor
every one acts upon the assumption that individual Weismann's now celebrated lectures. If the theory
peculiarities are transmitted, with or without selec- which Professor Weismann considers he has proved in
tion. Defects of body and mind, and liability to his laboratory is contradicted by the evidence of
succumb to certain diseases, are also only too well zoologists and paleontologists, as well as by the
known to be transmissible from one generation to universal practical experience of mankind, then it is
another. Deaf-mutes have children who are deaf- clear that laboratory work will not explain every-
mutes, though atavism hinders all the children from thing, and that the methods employed have been
inheriting this defect; and the same remark applies

But what shall we say when we are to persons with supernumerary toes and fingers. asked to accept a theory of which there is not one Where one parent has been the victim of phthisis or iota of tangible proof, which is, if anything, entirely of insanity, the children are in danger of succumbing contradicted by facts, and to accept this hypothesis to the same disease ; where both parents have fallen as the only side of the medal? Professor Weismann's victims, the chances are increased to a frightful theory in brief is that the “substance which forms. degree. It is almost impossible to imagine how the the foundation of all the phenomena of heredity, in my strongest prepossessions against heredity can hold opinion, can only be the substance of the germ-cells, out in the face, not only of countless arguments from and this substance transfers its hereditary tendencies science, but of the practical experience of mankind from generation to generation, and is always unin

fluenced in any corresponding manner by that which Mr. Wallace devotes one chapter only to the happens in the lifetime of the individual. If geological evidence of evolution ; but even in the these views be correct, all our ideas upon the transvery brief sketch he gives, there appears such over- formation of species require thorough modification, whelming evidence of the influence of heredity and its for the whole principle of evolution by means of effects in perfecting or aborting every organ of exercise (use and disuse) as proposed by Lamarck, animals, and the slight, fine modifications in certain and accepted in some eases by Darwin, entirely directions by which the changes from fossil to collapses." existing species have been effected, that one thinks he When we read that views held not only by cannot remain unconvinced, and that he must believe Lamarck, but by a host of illustrious men of science these modifications to be hereditary. We almost who have evidence at their command, which doubt the evidence of our eyes when we read this Lamarck and Darwin would have given worlds to passage,

“ There is now much reason to believe that possess, are to collapse before a certain theory, we the supposed inheritance of acquired modifications expect this theory to have been founded on somethat is of the effects of use and disuse, or of the thing that has at least been seen and observed. But it direct action of the environment–is not a fact." turns out that everything has to be “assumed.” The That is, we are to believe that all the modifications assumption is that only a part of the germ-cell is leading steadily upwards or downwards, the limbs used in the formation of the future animal; the perfected for speed of the horse and deer, the utter remainder of the cell as “germ-plasm” is reserved to absence of limbs in certain lizards, the specialisation be handed on to future generations. I have of the dentition of animals varying cusp by cusp and endeavoured to reproduce this idea by a rough tooth by tooth, the improvement in brain capacity diagram.

of rudimentary organs not only useless but dangerous to their essential substance is concerned, from the body their present possessors; we are gravely asked to of the individual, but they are derived directly from believe that all these modifications are the result the parent germ-cell.” The body (somatic) cells have, of a series of accidents occurring generation after Prof. Weismann repeatedly declares, nothing whate generation with results more and more marked, yet ever to do with the production of the germ-plasm. all uninherited and accidental ! Can any one who has been impressed with the grand simplicity and * " Biological Memoirs," p. 69. † Ibid. p. 168.

in all ages..

[ocr errors]

Yet he goes on to say that in all cases but that of characters has never been proved either by means of the Diptera,

* “generative cells arise from some of the direct observation or by experiment”! Such an later embryonic cells, and as these belong to a more assertion takes one's breath away, and makes one advanced ontogenetic stage in the development of wonder how far a very eminent man can be blinded the idioplasm,t we can only conclude that continuity by a theory. is maintained by assuming, as I do, that a small part This fatal tendency to adapt all facts to a foregone of the germ-plasm remains unchanged during the conclusion or a pet theory, and to minimise or ignore division of the first segmentation nucleus, and remains those that militate against it, the inability or the mixed with the idioplasm of a certain series of cells, unwillingness to look at both sides of the medal, is and that the formation of true germ-cells is brought seen in every department of science. The greatest · about at a certain point in the series by the appear. minds have been keenly alive to this danger, and nc ance of cells in which the germ-plasm becomes more illustrious example can be found of devotion to predominant. But if we accept this hypothesis, it truth at all costs than that of Newton. * His early does not matter theoretically ” [the italics are mine] theories on the law of gravitation were given up by “whether the germ-plasm becomes predominant in him as untenable, because of difficulties in reconciling the third, tenth, hundredth or millionth generation this law with the motions of the moon in her orbit. of cells.” In the same way, when we are dealing His study of the subject was only resumed after a with imaginary fortunes, it does not matter whether lapse of eleven years. Yet Newton's original calcuwe endow our hero with a thousand pounds a year or lations and his theory, were perfectly correct, only the a million. We seem landed in the happy old days original calculations were founded on an erroneous when one philosopher derived everything from fire, estimate of the length of a degree of latitude on the and another derived everything from water, and one earth's surface, which had to be corrected before hypothesis did just as well as another theoretically. theory and facts could agree. Many of the theories. The germ-plasm, which governs heredity, may exist of this illustrious Englishman “were left in an imor it may not; nobody has seen it, nor is likely to perfect state, for it is not in matters of science that it -see it unless the laws of optics change. Something is given to the same individual to invent and to bring conveys hereditary tendencies in a mannor as extra- to perfection. Their complete development required ordinary as it is mysterious. The hermaphrodite that several subsidiary sciences should be farther worm, which, if ontogeny does not deceive us, was advanced.” Fortunately no zealous friend was found the ancestor of the vertebrata, has impressed his nature to treat the conclusions of Newton as final, and dub upon all of us in the form of innumerable embryonic them “Newtonism'! The words of Mr. Proctor, and rudimentary structures. I

just quoted, may most fitly be employed in speaking Prof. Weismann may be perfectly correct so far as of the theories of one not less illustrious than Newton ; he maintains that heredity is the work of his germ- of one not less scrupulously anxious that his theories plasm, and the manner in which he works out this should be confirmed at all points by facts ; yet of one part of his theory is delightful. It is when he claims who could not see his grand hypothesis of evolution that variability is also the characteristic of his attain to its full development, because this required imaginary substance, to the exclusion of any influence that “several subsidiary sciences should be farther exerted by the somatic cells, that one refuses to advanced.” We do not hear of a School of Newton,' accept theory in place of facts. He will look only at priding itself on firmly making a stand at the point to his own side of the medal, though he appears sincerely which the great philosopher, with the imperfect data to wish to look at the other as well. Eyes do not at his command, had attained ; why in the name of atrophy through disuse ; short sight is not inherited ; science, or rather of simple common sense, should we a pointer doesn't point because his ancestors have hear of anything so absurd as a “Darwinian school.” been trained to point, but through a predisposition How earnestly would the great master himself have on the part of the germ. A predisposition to deprecated such an absurdity. His own mind was point on the part of a germ! He denies even the constantly open to the reception of new ideas. heredity of instinct, and says there is no transmission What mattered it to him that some of these ideas of acquired skill even in insects! Where facts are so threatened to conflict with the brilliant hypothesis, on overwhelmingly strong that it is impossible to meet which much of his fame rested, ie., the development them, he always says our knowledge on the subject of species through natural selection. All that he is still very defective." Let us only know more, and cared for-all that he had ever cared for in science, the germ will be proved all-potent. In the meantime was to ascertain the truth ; and again and again in he complacently says: “ The inheritance of acquired his works he deplores the imperfect data he had to

work from. Especially does he deplore the extreme "Biological Memoirs,” p. 197. Called usually germ-plasm.

imperfection of the geological record, and it is on “Introduction to Lectures on Pathology,” by J. Bland Sutton.

8. "Myopia may be attributed to the transmission of an accidental disposition on the part of the germ.” Pp. 86, 89,

"Encyclopædia Britannica,” articles Newton,' p. 441, 93, 95.

and 'Astronomy,' p. 756.

[merged small][ocr errors]
[ocr errors]
[ocr errors]

C,

this very point that the most gigantic strides have been made in our knowledge of late years.

I will quote a few passages showing the feelings of Darwin on this subject, and how far he was from making a fixed creed of his own conclusions.

“In many cases it is most difficult even to conjecture by what transitions organs have arrived at their present state."*

“ In searching for the gradations through which an organ in any species has been perfected, we ought to look exclusively to its lineal progenitors ; but this is scarcely ever possible." +

It is hardly necessary to say what brilliant work has elucidated these difficulties of late years. Embryologists have traced the stages through which every part of the future animal passes on its way to its own form of differentiation; as for instance the modifications of the bones in the leg and wing of the chick, in which, at an early period the indications of a former five-toed condition can be seen ; the germs of teeth destined never to cut the gum, and the consolidation of the bones in ruminants and equidæ ; and the three sets of kidneys in vertebrates.

Palæontologists have had successes as brilliant ; they can show the phylogeny of an immense number of our present mammals, whilst the embryologists have demonstrated their ontogeny: the “lineal progenitors” have been found. Darwin says I, “Two forms can seldom be connected by intermediate varieties, and thus proved to be the same species, until many specimens are collected from many places ; and with fossil species this can rarely be done. We shall perhaps best perceive the improbability of our being able to connect species by numerous fine intermediate fossil links, by asking ourselves whether, for instance, geologists at some future period will be able to prove that our different breeds of cattle, sheep, horses, and dogs are descended from a single stock or from several aboriginal stocks. ... This could be effected only by his discovering in a fossil state numerous intermediate gradations; and such success is improbable in the highest degree.” This success, which the great master thought "improbable in the highest degree” has been attained ; and the “numerous, fine, intermediate gradations in the fossil state," have been traced.

Again, in arguing with writers who assert the immutability of species by asserting that geology yields no linking forms, he says, $ “ If we take a genus having a score of species, recent and extinct, and destroy four-fifths of them, no one doubts that the remainder will stand much more distinct from each other. . . . What geological research has not revealed is the former existence of infinitely numerous gradations, as fine as existing varieties, connecting

Fig. 7:-a, reproductive cell ; b, nucleus, which after extrusios of the polar globules will form the future animal or plant ;

germ-plasm” left over to carry on the qualities of ancestors, and transferred from generation to generation. Whatever changes occur in an animal are due entirely to

modifications of the “ germ-plasm." only of our “different breeds of cattle, sheep, horses and dogs,” but those of the bear, the cat, the weasel, the rhinoceros, the camel and of countless other animals would be accurately known.*

And, with regard to his own special hypothesis of evolution through natural selection, he speaks again and again of our ignorance of the causes which have given rise to those variations upon which natural selection has to work. The battle which Darwin had to fight was to prove the evolution and consequent changeability of species, in opposition to opponents who believed in the special creation and unchangeability of species. Having had that great battle won for them, scientific men have had leisure to turn their attention to the cause of the variations controlling evolution. Later in his life, after having borne the burden and heat of the day, Darwin had more leisure to turn his own attention to this most important question. The following extracts will exemplify the earlier and later phases of his opinions on this subject :-“Variations appear to arise from the same unknown causes acting on the cerebral organization, which induce slight variations or individual differences in other parts of the body; and these variations, owing to our ignorance, are often said to arise spontaneously.”+ (The italics are mine.) After speaking of the number of facts collected with respect to the transmission of the most trifling, as well as of the most important characters in man, and also in domestic animals, he says : “With regard to the causes of variability, we are in all cases very ignorant." And again, he speaks of the “complex and little-known laws governing the production of varieties,” being “the same, so far as we can judge, as the laws which have governed the production of distinct species." I

together nearly all existing and extinct species. But

this ought not to be expected.” So far is the great

“Origin of the Fittest" (Professor Cope); “Les Ancêtres de nos Animaux (Gaudry); “The Mammalia (Oscar Schmidt. “Descent of Man,"

".pp. 38, 110, III. İ “Origin of Species," p. 415.

* “Origin of Specics," p. 156. # Ibid. p. 279.

+ Ibid. p. 144.

Ibid. p. 280.

The last passages I shall quote are pathetic, in view of the persistent attempts to connect Darwin

FE.

F

T

Fig. 8.

FE.

appears that I formerly underrated the frequency and value of these later forms of variation” (viz. adaptive structures which have arisen by the direct action of external conditions). “But as my conclusions have lately been much misrepresented, and it has been stated that I attribute the modification of species exclusively to natural selection, I may be permitted to remark that .... I placed in a most conspicuous position the following words : 'I am convinced that natural selection has been the main, but not the exclusive means of modification.' This has been of no avail. Great is the power of steady misrepresenta tion, but the history of science shows that fortunately this power does not long endure." But his views were gradually changing as to the importance of the action of the environment in evolution; and in one of his later letters he says: “In my opinion the greatest error which I have committed has been not allowing sufficient weight to the direct action of the environment, independently of natural selection.” *

We have an equally fine instance of the willingness to accept new ideas, however much they might apparently be in opposition to his own views, in the attitude of Mr. Herbert Spencer towards this very theory of natural selection. As early as 1864, in his “Principles of Biology," + with that prophetic instinct which characterises genius, he had laid down those principles of evolution now often spoken of as Neo-Lamarckian. For Lamarck, animated by the same prophetic genius, had foreseen the prepotent power of the action of environment, though his data were so imperfect, so apparently empirical, that his theory was laughed to scorn. Mr. Herbert Spencer had pointed out the influence of the environment on the very simplest unicellular organisms, had traced it up to more and more complex organisms, had shown its influence upon every part of the body and its struggle with atavism, or the principle of heredity so strongly possessed by all animal and vegetable cells. Of the many hundreds of brilliant discoveries in chemistry, pathology, biology, and paleontology, which from every side now confirm his theories, he could not then avail himself; yet his conclusions are confirmed in almost every instance by what these sciences have revealed to us. Yet in his “Factors of Organic Evolution,” published twenty-two years later, he is ready to resign his victor's wreath to Darwin, he acknowledges him as a teacher, and bears witness to the priceless services rendered to the cause of the evolutionary theory by the publication of the “ Origin of Species.” He sees both sides of the medal, but he does not at that date appear to have grasped the fact that each side belongs to the same medal, and that natural selection is only one manifestation of that great Law of the Action of the Environment on all organic beings, of which he was

[blocks in formation]

• “Life and Letters of Charles Darwin,” vol. ii., p. 338.

+ “Principles of Biology,” pp. 7, 12, 72, 74, 75, 80, 83, 226, 235, 294, 296, 311, 322, &c.

* “Origin of Species," p. 421 (1872).

may be,

66

[ocr errors]

the brillant exponent. In its simplest manifestation methods of micro-biological research, the nature of it influences the protoplasm of unicellular organisms ; various ferments; production of Ptomaines ; special in its more complicated manifestations it decrees the ferments; the various substances secreted by extermination of the South Sea Islanders, by the Microbes ; the action of heat on microbes and their aliep civilisation, the diseases, and the rum of the spores ; an account of the researches of Koch, Klein, white man. It dwarfs the pines on the tundras of Pasteur, Bert, Parsons, Duclaux, Forster, and others, Siberia till they finally dwindle into trailing weeds to which we are pleased to see the author has added four to five inches high ; it increases the size, or the his own, which are not the least interesting. There speed, or the marketable value, whatever

are also lengthy and varied chapters on Germicides of our domestic animals; it has changed the fierce and antiparasitic therapeutics ; the General Biology wolf and the cowardly jackal into the only animal of the Microbes of Rabies, Yellow Fever, Pleurowhich has won, by its high mental and moral pneumonia, Foot-and-mouth Disease, Cattle Plague, qualities, the title of the friend of man.* It has been Pyamia, Septicoemia, Puerperal Fever, Syphilisproved that the action of the environment, and no tuberculosis, Anthrax, Swine Fever, &c. The last mysterious vital force" preserves the liquid con. chapter is an excellent summary of the recent. dition of the blood in living veins, or causes its experiments on the destruction of microbes in infeccoagulation. No function is too high or too low for tious diseases, in which, of course, those of Professor its all-pervading influence ; just as the law of gravitation Koch occupy a prominent position. Dr. Griffiths has acts upon the minutest speck of matter, as inflexibly produced a useful as well as a thoroughly good as it acts upon the solar system.

book. I trust that in this necessarily imperfect sketch I Astronomical Lessons, by J. E. Gore (London: have at least shown how unjustifiable is the attempt Sutton, Drowley, & Co.). We cordially recomto associate the great name of Darwin with the un- mend this well got up little book, the work of a wellprogressive school which arrogates to itself the right known astronomer and astronomical writer, as one of of claiming to be his special disciples. To demon. the best introductions to the study of the "noble strate fully how baseless in ascertained fact is science we have yet come across. It contains Professor Weismann's theory of “germ-plasm ” would twenty-two short chapters dealing with a large and require a special article ; but I have endeavoured to general range of astronomical knowledge, all of indicate a few of its weak points, and to show its course brought up to the most recent date. The constant need of assumptions as bases of reasoning. book is well illustrated.

Applied Geography, by J. Scott Keltie (London:

George Philip & Son). This is altogether a novel NOTES ON NEW BOOKS.

and acceptable departure from the too traditional

method of teaching geography. Much of its conESEARCHES ON MICRO-ORGANISMS,

tents have appeared as articles in leading magazines, by Dr. A. B. Griffiths London ; Baillière,

lectures given before the Society of Arts, the College Tindal, & Cox). Dr. Griffiths is well known as one

of Preceptors, the Bankers' Institute, etc., and the of the most painstaking and industrious of our

book is illustrated by excellent illustrative maps. younger school of scientists, and he has here pro

It contains five chapters headed as follows :duced a very useful manual of reference, which

“Preliminary Considerations,” “Geography applied includes an account of all the recent experiments on

to Commerce,” “The Geography of Africa in its the destruction of Microbes in various infectious

Bearings on the Development of the Continent."" diseases, and is illustrated by fifty-two woodcuts,

(two chapters on this all-important subject), “The Just at present Bacteriology is dominant, ten years

British Empire," and “ Some Common Com. ago hardly a few scores of people knew what the

modities.” term meant. A general knowledge of the subject is

London of the Past, by J. Ashton Ainscough. now incumbent on all medical men, apothecaries, and

(London : Elliot Stock). This is a small, delightfully journalists. Dr. Griffiths, however, does not claim

written and accurate history of the most wonderful his book to be a manual of Bacteriology, after the

and interesting city in the world. It is a straightmanner of Dr. Crookshank. It is rather an exposé of the researches which throw light on the pathology

forward narrative, neither encumbered with comment.

nor laden with petty details. and therapeutics of certain infectious diseases.

Elementary Treatise on Hydrodynamics and Sound, Nevertheless, it throws a very large cast.net over the

by A. B. Bassett, F.R.S. (Cambridge: Deighton, whole field of the subject, including an outline of the

Bell & Co.). The author's fame as a mathematician natural history of Microbes in general; their

is well known, and his previous works on these microscopical examination, classification, cultivation,

special subjects have deservedly acquired for him the distribution in earth, air, and water; the various

rank of an authority. It is a most useful work on

mathematical physics, and includes much which will * For the ancestry of the dog, see "The Mammalia,” by Oscar Schmidt. International Scientific Series.

prove valuable to mathematical electricians par

RESEA

« EelmineJätka »