The detection of transitional forms would be rendered more difficult on rising point of land.

The distribution therefore in the above enumerated points, even the trivial ones, which on any other can be viewed as so many ultimate facts, all follow a simple manner on the theory of the occurrence of species by and being adapted by selection to , conjoined with their power of dispersal, and the steady geographico-geological changes which are now in progress and which undoubtedly have taken place. Ought to state the opinion of the immutability of species and the creation by so many separate acts of will of the Creator{134}.{134} Effect of climate on stationary island and on continent, but continent once island. Moreover repeated oscillations fresh diffusion when non-united, then isolation, when rising again immigration prevented, new habitats formed, new species, when united free immigration, hence uniform characters.Hence more forms the island. Mountain summits. Why not true species. First let us recall in Part I, conditions of variation: change of conditions during several generations, and if frequently altered so much better [perhaps excess of food]. Secondly, continued selection [while in wild state]. Thirdly, isolation in all or nearly all,--as well to recall advantages of.[In continent, if we look to terrestrial animal, long continued change might go on, which would only cause change in numerical number : if continued long enough might ultimately affect all, though to most continents chance of immigration. Some few of whole body of species must be long affected and entire selection working same way. But here isolation absent, without barrier, cut off such . We can see advantage of isolation. But let us take case of island thrown up by volcanic agency at some distances, here we should have occasional visitants, only in few numbers and exposed to new conditions and more important,--a quite new grouping of organic beings, which would open out new sources of subsistence, or control old ones. The number would be few, can old have the very best opportunity.

< p="">390.> Moreover as the island continued changing,--continued slow changes, river, marshes, lakes, mountains &c. &c., new races as successively formed and a fresh occasional visitant.If island formed continent, some species would emerge and immigrate. Everyone admits continents. We can see why Galapagos and C. Verde differ ], depressed and raised.We can see from this repeated action and the time required for a continent, why many more forms than in New Zealand no mammals or other cla.s.ses . We can at once see how it comes when there has been an old channel of migration,--Cordilleras; we can see why Indian Asiatic Flora,--[why species] having a wide range gives better chance of some arriving at new points and being selected, and adapted to new ends. I need hardly remark no necessity for change.Finally, as continent (most extinction during formation of continent) is formed after repeated elevation and depression, and interchange of species we might foretell much extinction, and that the survivor would belong to same type, as the extinct, in same manner as different part of same continent, which were once separated by s.p.a.ce as they are by time < p="">339 and 349>.As all mammals have descended from one stock, we ought to expect that every continent has been at some time connected, hence obliteration of present ranges. I do not mean that the fossil mammifers found in S. America are the lineal successors chance of fewness. Moreover in every case from very existence of genera and species only few at one time will leave progeny, under form of new species, to distant ages; and the more distant the ages the fewer the progenitors. An observation may be here appended, bad chance of preservation on rising island, the nurseries of new species, appeal to experience < p="">i. p. 292>. This observation may be extended, that in all cases, subsiding land must be, in early stages, less favourable to formation of new species; but it will isolate them, and then if land recommences rising how favourable. As preoccupation is bar to diffusion to species, so would it be to a selected variety. But it would not be if that variety was better fitted to some not fully occupied station; so during elevation or the formation of new stations, is scene for new species. But during elevation not favourable to preservation of fossil (except in caverns ); when subsidence highly favourable in early stages to preservation of fossils; when subsidence, less sediment. So that our strata, as general rule will be the tomb of old species (not undergoing any change) when rising land the nursery. But if there be vestige will generally be preserved to future ages, the new ones will not be entombed till fresh subsidence supervenes. In this long gap we shall have no record: so that wonderful if we should get transitional forms. I do not mean every stage, for we cannot expect that, as before shown, until geologists will be prepared to say that although under unnaturally favourable condition we can trace in future ages short-horn and Herefordshire .{Note 115} -- VII. Looking now to the affinities of organisms, without relation to their distribution, and taking all fossil and recent, we see the degrees of relationship are of different degrees and arbitrary,--sub-genera,--genera,--sub-families, families, orders and cla.s.ses and kingdoms. The kind of cla.s.sification which everyone feels is most correct is called the natural system, but no can define this. If we say with Whewell undefined instinct of the importance of organs{135}, we have no means in lower animals of saying which is most important, and yet everyone feels that some one system alone deserves to be called natural. The true relationship of organisms is brought before one by considering relations of a.n.a.logy, an otter-like animal amongst mammalia and an otter amongst marsupials. In such cases external resemblance and habit of life and _the final end of whole organization_ very strong, yet no relation{136}. Naturalists cannot avoid these terms of relation and affinity though they use them metaphorically. If used in simple earnestness the natural system ought to be a genealogical ; and our knowledge of the points which are most easily affected in transmission are those which we least value in considering the natural system, and practically when we find they do vary we regard them of less value{137}. In cla.s.sifying varieties the same language is used and the same kind of division: here also (in pine-apple){138} we talk of the natural cla.s.sification, overlooking similarity of the fruits, because whole plant differs. The origin of sub-genera, genera, &c., &c., is not difficult on notion of genealogical succession, and accords with what we know of similar gradations of affinity in domesticated organisms. In the same region the organic beings are related to each other and the external conditions in many physical respects are allied{139} and their differences of same kind, and therefore when a new species has been selected and has obtained a place in the economy of nature, we may suppose that generally it will tend to extend its range during geographical changes, and thus, becoming isolated and exposed to new conditions, will slightly alter and its structure by selection become slightly remodified, thus we should get species of a sub-genus and genus,--as varieties of merino-sheep,--varieties of British and Indian cattle. Fresh species might go on forming and others become extinct and all might become extinct, and then we should have According to mere chance every existing species may generate another, but if any species, A, in changing gets an advantage and that advantage (whatever it may be, intellect, &c., &c., or some particular structure or const.i.tution) is inherited{140}, A will be the progenitor of several genera or even families in the hard struggle of nature. A will go on beating out other forms, it might come that A would people earth,--we may now not have one descendant on our globe of the one or several original creations{141}. External conditions air, earth, water being same{142} on globe, and the communication not being perfect, organisms of widely different descent might become adapted to the same end and then we should have cases of a.n.a.logy{143}, [they might even tend to become numerically representative]. From this often happening each of the great divisions of nature would have their representative eminently adapted to earth, to and then these great divisions would show numerical relations in their cla.s.sification.{135} After "organs" is inserted, apparently as an afterthought:--"no, and instance metamorphosis, afterwards explicable."{136} For a.n.a.logical resemblances see _Origin_, Ed. i. p. 427, vi.p. 582.{137} "Practically when naturalists are at work, they do not trouble themselves about the physiological value of the characters.... If they find a character nearly uniform, ... they use it as one of high value," _Origin_, Ed. i. p. 417, vi. p. 573.{138} "We are cautioned ... not to cla.s.s two varieties of the pine-apple together, merely because their fruit, though the most important part, happens to be nearly identical," _Origin_, Ed. i.p. 423, vi. p. 579.{139} The whole of this pa.s.sage is obscure, but the text is quite clear, except for one illegible word.{140} "just as it is not likely every present breed of fancy birds and cattle will propagate, only some of the best."{141} This suggests that the author was not far from the principle of divergence on which he afterwards laid so much stress. See _Origin_, Ed. i. p. 111, vi. p. 134, also _Life and Letters_, i. p.84.{142} That is to say the same conditions occurring in different parts of the globe.{143} The position of the following is uncertain, "greyhound and racehorse have an a.n.a.logy to each other." The same comparison occurs in the _Origin_, Ed. i. p. 427, vi. p. 583.{144} _Air_ is evidently intended; in the MS. _water_ is written twice.-- VIII. UNITY [OR SIMILARITY] OF TYPE IN THE GREAT CLa.s.sES.Nothing more wonderful in Nat. Hist. than looking at the vast number of organisms, recent and fossil, exposed to the most diverse conditions, living in the most distant climes, and at immensely remote periods, fitted to wholely different ends, yet to find large groups united by a similar type of structure. When we for instance see bat, horse, porpoise-fin, hand, all built on same structure{145}, having bones{146} with same name, we see there is some deep bond of union between them{147}, to ill.u.s.trate this is the foundation and objects what is called the Natural System; and which is foundation of distinction of true and adaptive characters{148}. Now this wonderful fact of hand, hoof, wing, paddle and claw being the same, is at once explicable on the principle of some parent-forms, which might either be or walking animals, becoming through infinite number of small selections adapted to various conditions. We know that proportion, size, shape of bones and their accompanying soft parts vary, and hence constant selection would alter, to almost any purpose the framework of an organism, but yet would leave a general, even closest similarity in it.{145} Written between the lines occurs:--"extend to birds and other cla.s.ses."{146} Written between the lines occurs:--"many bones merely represented."{147} In the _Origin_, Ed. i. p. 434, vi. p. 595, the term _morphology_ is taken as including _unity of type_. The paddle of the porpoise and the wing of the bat are there used as instances of morphological resemblance.{148} The sentence is difficult to decipher.[We know the number of similar parts, as vertebrae and ribs can vary, hence this also we might expect.] Also the changes carried on to a certain point, doubtless type will be lost, and this is case with Plesiosaurus{149}. The unity of type in past and present ages of certain great divisions thus undoubtedly receives the simplest explanation.{149} In the _Origin_, Ed. i. p. 436, vi. p. 598, the author speaks of the "general pattern" being obscured in the paddles of "extinct gigantic sea-lizards."There is another cla.s.s of allied and almost identical facts, admitted by the soberest physiologists, [from the study of a certain set of organs in a group of organisms] and refers to a unity of type of different organs in the same individual, denominated the science of "Morphology." The discovered by beautiful and regular series, and in the case of plants from monstrous changes, that certain organs in an individual are other organs metamorphosed. Thus every botanist considers petals, nectaries, stamens, pistils, germen as metamorphosed leaf. They thus explain, in the most lucid manner, the position and number of all parts of the flower, and the curious conversion under cultivation of one part into another. The complicated double set of jaws and palpi of crustaceans{150}, and all insects are considered as metamorphosed and to see the series is to admit this phraseology.The skulls of the vertebrates are undoubtedly composed of three metamorphosed vertebrae; thus we can understand the strange form of the separate bones which compose the casket holding man's brain. These{151} facts differ but slightly from those of last section, if with wing, paddle, hand and hoof, some common structure was yet visible, or could be made out by a series of occasional monstrous conversions, and if traces could be discovered of whole having once existed as walking or swimming instruments, these organs would be said to be metamorphosed, as it is they are only said to exhibit a common type.{150} See _Origin_, Ed. i. p. 437, vi. p. 599.{151} The following pa.s.sage seems to have been meant to precede the sentence beginning "These facts":--"It is evident, that when in each individual species, organs are metamorph. a unity of type extends."This distinction is not drawn by physiologists, and is only implied by some by their general manner of writing. These facts, though affecting every organic being on the face of the globe, which has existed, or does exist, can only be viewed by the Creationist as ultimate and inexplicable facts. But this unity of type through the individuals of a group, and this metamorphosis of the same organ into other organs, adapted to diverse use, necessarily follows on the theory of descent{152}. For let us take case of Vertebrata, which if{153} they descended from one parent and by this theory all the Vertebrata have been altered by slow degrees, such as we see in domestic animals. We know that proportions alter, and even that occasionally numbers of vertebrae alter, that parts become soldered, that parts are lost, as tail and toes, but we know here we can see that possibly a walking organ might be converted into swimming or into a gliding organ and so on to a flying organ. But such gradual changes would not alter the unity of type in their descendants, as parts lost and soldered and vertebrae. But we can see that if this carried to extreme, unity lost,--Plesiosaurus. Here we have seen the same organ is formed different purposes : and if, in several orders of vertebrata, we could trace origin spinous processes and monstrosities &c. we should say, instead of there existing a unity of type, morphology{154}, as we do when we trace the head as being the vertebrae metamorphosed. Be it observed that Naturalists, as they use terms of affinity without attaching real meaning, here also they are obliged to use metamorphosis, without meaning that any parent of crustacean was really an animal with as many legs as crustacean has jaws. The theory of descent at once explains these wonderful facts.{152} This is, I believe, the first place in which the author uses the words "theory of descent."{153} The sentence should probably run, "Let us take the case of the vertebrata: if we a.s.sume them to be descended from one parent, then by this theory they have been altered &c."{154} That is "we should call it a morphological fact."Now few of the physiologists who use this language really suppose that the parent of insect with the metamorphosed jaw, was an insect with [more] so many legs, or that the parent of flowering plants, originally had no stamens, or pistils or petals, but some other means of propagation,--and so in other cases. Now according to our theory during the infinite number of changes, we might expect that an organ used for a purpose might be used for a different one by his descendant, as must have been the case by our theory with the bat, porpoise, horse, &c., which are descended from one parent. And if it so chanced that traces of the former use and structure of the part should be retained, which is manifestly possible if not probable, then we should have the organs, on which morphology is founded and which instead of being metaphorical becomes plain and {155} In the _Origin_, Ed. i. p. 438, vi. p. 602, the author, referring to the expressions used by naturalists in regard to morphology and metamorphosis, says "On my view these terms may be used literally." This general unity of type in great groups of organisms (including of course these morphological cases) displays itself in a most striking manner in the stages through which the foetus pa.s.ses{156}.In early stage, the wing of bat, hoof, hand, paddle are not to be distinguished. At a still earlier there is no difference between fish, bird, &c. &c. and mammal. It is not that they cannot be distinguished, but the arteries{157} . It is not true that one pa.s.ses through the form of a lower group, though no doubt fish more nearly related to foetal state{158}.{156} See _Origin_, Ed. i. p. 439, vi. p. 605.{157} In the _Origin_, Ed. i. p. 440, vi. p. 606, the author argues that the "loop-like course of the arteries" in the vertebrate embryo has no direct relation to the conditions of existence.{158} The following pa.s.sages are written across the page:--"They pa.s.s through the same phases, but some, generally called the higher groups, are further metamorphosed.? Degradation and complication? no tendency to perfection.? Justly argued against Lamarck?"This similarity at the earliest stage is remarkably shown in the course of the arteries which become greatly altered, as foetus advances in life and a.s.sumes the widely different course and number which characterize full-grown fish and mammals. How wonderful that in egg, in water or air, or in womb of mother, artery{159} should run in same course.