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TEE POPULAR SCIENCE MONTELY.— SUPPLEMENT. 



sistent, but also demonstrates how great an al- 

 teration in the nature of a living organism a 

 change of surrounding conditions may induce. 

 As Mr. G. H. Lewes remarks: "This aquatic or- 

 ganization has no reference to the future life of 

 the animal, nor has it any adaptation to its embry- 

 onic condition ; it has solely reference to ances- 

 tral adaptations, it repeats a phase in the devel- 

 opment of its progenitors." That the change in 

 the Alpine salamander's mode of development has, 

 in reality, been one entirely dependent upon ex- 

 ternal causes, is a suggestion which, as made by 

 Frixulein von Chauvin, carries weight with it in 

 support of the idea of the close relationship be- 

 tween living beings and their environments. 

 Want of food would thus be a condition which 

 could scarcely be conceived as having driven the 

 Alpine newt to its high habitat, since the dietary 

 would become scarcer and more difficult to obtain 

 the higher the altitude it reached. More proba- 

 ble is the idea that slow elevation of the land-sur- 

 face was the cause of the change in habits and de- 

 velopment. A slow rise of land would imply an 

 equally gradual alteration of habits, as water-pools 

 became less numerous. The young, at first bom 

 alive and gilled, would be produced at less frequent 

 intervals and in fewer numbers, while they would 

 also be retained for longer periods within the 

 parent-body. This view accords with the actual 

 detail of the animal's life. For only two young 

 are produced at a birth by these animals ; other 

 eggs serving as food for the developing minority. 

 This latter remarkable feature of the sustenance 

 of the young by their immature brethren can, of 

 course, be regarded only in the light of an ac- 

 quired condition, and as one which has arisen out 

 of the needs and necessities of the species. 



The conclusions at which the earnest and 

 unbiased student of Nature may arrive regard- 

 ing any points involved in his studies may very 

 frequently be found to be greatly at variance 

 with the notions of natural law and order that 

 prevail in the world at large. But, as Tyndall 

 has well remarked, " In the choice of probabili- 

 ties the thoughtful mind is forced to take a 

 side ; " and the attitude of the seeking mind 

 toward natural phenomena and their explanation 

 must ever be that of estimating causes by the 

 likelihood and value of the evidence brought to 

 light. Judged by the standard of once-popular 

 faith, that the living things of the world were 

 created as we find them, the cases of the flat- 

 fishes and amphibians do not seem very promis- 

 ing, it must be confessed. But the choice of a 

 side admits of no hesitancy here. The evidence 



that outward and mechanical agencies, operating 

 upon living bodies and correlating themselves with 

 the forces and ways of life, are the causes of the 

 peculiarities we have noticed, is too forcible to 

 be for a moment doubted. A peculiar form or 

 shape of body, a rise of land, and the influence 

 of the " law of likeness " in perpetuating the 

 variations thereby produced — such are the causes 

 and means through which the greater portion of 

 the world of life has been and is still being 

 moulded. How much in any case may be due to 

 the influence of outward causes, and what amount 

 of power we are to ascribe to the internal forces 

 and constitution of living beings, no one may 

 dogmatically assert. But our ignorance of the 

 exact relations of these causes to outward con- 

 ditions will not militate in any way against the 

 recognition of the power of the latter to effect 

 change and alteration in living Nature. In the 

 axolotl, the external influences of a land-life are 

 seen to cause gills and tail-fin to shrivel and ul- 

 timately to disappear. In the young salamander, 

 on the contrary, the vital process of absorption 

 must apparently be credited with the chief share 

 of the work of modification, and of causing gills 

 and other larval structures to become abortive. 

 In the flatfishes a mechanical cause, namely, a 

 tendency to lop-sidedness, presents us with the 

 primary reason for the peculiar development and 

 position of the eyes. And we thus see, in the 

 case of the axolotl, the mechanical beginnings of 

 actions which in the flatfishes and Alpine sala- 

 mander have been operating through long pe- 

 riods of time, and which, through the agency of 

 the law of likeness and heredity, have become 

 well-defined characters of the species. Admit- 

 ting that variations may begin from without, that 

 they are transmitted to posterity, and that as 

 time passes they may come, as we have seen, to 

 represent the " way of life," we are thus placed 

 in possession of rational ideas regarding the 

 manner in which cause and effect in one phase 

 of Nature are related. And if it be urged that 

 great are the mysteries which yet beset the 

 " ways of life," the knowledge that we have ob- 

 tained of even a small part of the order of Na- 

 ture may still lead toward a fuller and wider 

 comprehension of the universe and its laws. 

 We are now only studying the alphabet of Na- 

 ture. A little patience — and we may be able to 

 say with Shakespeare's soothsayer: 



" In Nature's infinite book of secrecy 

 A little I can read." 



— The Gentleman 's Magazine. 



