358 



♦ KNOWLEDGE ♦ 



[Dec. 14, 1883. 



the impnlse which leads the pinioned goose to scramble northward 

 would lead our bird over the trackless waters ; and that, by the aid 

 of the unknown power by which many animals (and savage men) 

 can retain a true course, it would safely cross the sea now covering 

 the submerged path of its ancient journey. 



The section on instinctive fear is even more interesting 

 than that on migration, and requires and receives delicate 

 handling and cautious investigation ; it is marked by all 

 the features which are so characteristic of Darwin's pre- 

 vious works, including that scepticism which made him 

 slow to accept, without personal examination, instances 

 which seemed most strongly to lead to the conclusion that 

 he was inclined to accept. He shows that in unfrequented 

 islands the wild animals have rarely any fear of man, 

 and that this feeling is only acquired after considerable 

 familiarity with the methods of the animals' most dangerous 

 enemy. He then, in considering the manifestations of fear 

 and ,the methods adopted to escape the dreaded danger, 

 refers to animals feigning, as it is said, death, " an un- 

 known state to every living creature," which seemed to 

 Darwin a remarkable instinct ; so he resolved to test it in 

 the case of insects. He says : — 



Hence I carefully noted the simulated positions of 17 different 

 kinds of insects, belonging to the most distinct genera, both poor 

 and first-rate shammers; afterwards I procured natui-ally dead 

 specimens of some of these insects, others I killed with camphor 

 by an easy, slow death. The result was that in no one instance 

 was the attitude exactly the same, and in several instances the 

 attitude of the feigners and of the really dead were as unlike as 

 they could possibly be. 



Of course, this does not bear at all against the hypo- 

 thesis that these insects assumed their motionless attitude 

 through fear, but only disproves the prevalent belief that 

 they instinctively or intentionally feigned death. More- 

 over, Mr. Romanes refers in the text of his work to 

 several very remarkable and well-authenticated instances 

 among the higher animals of the assumption of attitudes so 

 deatli-like as to deceive the most experienced observers. 



Equally interesting and much fuller of instances are the 

 sections on nest-building among birds and the construction 

 of habitations by the higher animals, as the beaver. Nests 

 especially, Darwin shows, have all forms. He says : — 



In the nests of birds we have an unusually perfect series, from 

 those which build none, but lay on the bare ground, to others which 

 make a most imperfect and simple nest, to others more perfect, and 

 80 on till we arrive at marvellous structures, rivalling the weaver's 

 art. 



He shows that birds, under certain conditions, where the 

 end can be otherwise accomplished, will lose the instinct 

 of incubation entirely, and that, in fine, nest-building in 

 itself, and the multifarious forms which nests assume are 

 determined by the principle of natural selection, by adapta- 

 tion to special conditions. 



Darwin then goes on to consider several instances of 

 special difficulty — cases, for example, of an instinct ap- 

 pearing only once in the lifetime of an animal, which, 

 however, he proves are perfectly explicable on the great 

 principle, which under liis hands has unravelled so many 

 mysteries, the principle that it is a matter of life and death 

 to all organisms to be able to adapt themselves to their 

 circumstances ; and the instances which he gives of dis- 

 advantageous instincts only serve to confirm the truth of 

 the great principle. In his conclusion, he says : — 



We have in this chapter chiefly considered the instincts of 

 animals under the point of view, whether it is possible that they 

 could have been acquired through the means indicated on our 

 theory, or whether, even if the simpler ones could have been thus 

 acquired, others are so complex and wonderful that they must have 

 been specially endowed, and thus overthrow the theory. 



He then goes on to refer summarily to the various forms 

 and modifications in which it has been found that instincts 

 present themselves : — 



Bearing in mind that in a state of nature instincts do certainly 

 vary in some slight degree ; bearing in mind how very generally 

 we find in allied but distinct animals a gradation in the more com- 

 plex instincts, which shows that it is at least possible that a com- 

 plex instinct might have been acquired by successive steps, and 

 which, moreover, generally indicates, according to our theory, the 

 actual steps by whicli the instinct has been acquired, inasmuch as 

 we suppose allied instincts to have branched off at different stages 

 of descent from a common ancestor, and therefore to have retained, 

 more or less unaltered, the instincts of the several lineal ancestral 

 forms of any one species — bearing all this in mind, together with 

 the certainty that instincts are as important to animals as their 

 generally correlated structures, and that, in the struggle for life 

 under changing conditions, slight modifications of instinct could 

 hardly fail occasionally to be profitable to individuals, I can see no 

 overwhelming difficulty on our theory. Even in the most marvellous 

 instinct known, that of the cells of the hive bee, we have seen 

 how a simple instinctive action may lead to results which fill the 

 mind with astonishment The imperfections and mis- 

 takes of instinct on our theory cease to be surprising ; indeed, it 

 would be wonderful that far more numerous and flagrant cases 

 could not be detected, if it were not that a species which has failed 

 to become modified and so far perfected in its instincts that it 

 could continue struggling with the co-inhabitants of the same region 

 would simply add one more to the myriads which have become 

 extinct. It may not be logical, but to my imagination it is far 

 more satisfactory, to look at the young cuckoo ejecting its foster- 

 brothers, ants making slaves, the larvae of the ichneumidaj feeding 

 within the live bodies of their prey, cats playing with mice, otters 

 and cormorants with living fish, not as instincts specially given by 

 the Creator, but as very small parts of one general law leading to 

 the advancement of all organic bodies — multiply, vary, let the 

 strongest live and the weakest die. 



Such, then, is the clear and unmistakable conclusion of 

 the posthumous fragment which Mr. Romanes has given 

 in full to the world. It is the keystone, as it were, to the 

 marvellous structure which, oppressed by almost constant 

 suffering, Darwin spent his life in rearing. It may in the 

 future be overtopped ; it may, indeed, be only the central 

 foundation for some larger and loftier structure, from the 

 summit of which future generations may be able, with 

 improved instruments, to see much farther into the mystery 

 that surrounds us than we can ever hope to do ; but it is 

 impossible to conceive that it can ever be entirely swept 

 away, that it can cease to be an important factor in solving 

 the complex problems which will continue to present them- 

 selves to science, or that its author can ever be placed on a 

 lower pedestal than that allotted to him by the greatest 

 among his contemporaries. — Times. 



HOW IS A LIFE ASSURANCE SOCIETY 

 WORKED ? 



LET us hope there are not a few among our readers 

 who are able to appreciate the advantages of life 

 assurance. To such, a brief explanation of the principles 

 upon which a life assurance society is worked may not be 

 unacceptable ; and at any rate it may show them and others 

 upon what a secure system such .societies are based, and 

 may enable them the better to judge of the working and 

 stability of any particular office. 



Now, if the duration of life and the rate of interest 

 were certain, any one could, by investing a certain sum 

 at compound interest, secure a known amount at his death. 

 To make this plainer : if every one died at 60, and the 

 universal rate of interest were 3 per cent., a man of iO, 

 by investing £1 a year at compound interest, would have 

 accumulated at his death iT.'Ji; and a man at 45, by 

 doing likewise, would have £18-6. If then either of them 



