MIMICRY. 361 



that truth may exist between the two antagonists, for it seems 

 certain we have not yet all the explanations of these mimetic 

 disguises, and discussion may well precede a universal dogma of 

 its causation. Because a phenomenon is frequent in nature, it is 

 not necessarily universal. For instance, the metamorphosis in 

 the early lives of Frogs is an observation of so general a nature 

 as to indicate a constant law ; but a land Frog in the Solomon 

 Islands (Rana opisthodon) lays very large eggs in the crevices of 

 rocks, and from these emerge fully- developed Frogs.* We join 

 issue with Prof. Tyler when he states, " Natural science does 

 not deal in demonstrations, it rests upon the doctrine of pro- 

 babilities; just as we have to order our whole lives according to 

 this doctrine."! This is a cardinal doctrine in natural and 

 apologetic theology, but is the very antithesis of science, natural 

 or otherwise. The man who orders his whole life on probabilities 

 will probably arrive at the conclusion that hope is a very good 

 breakfast, but a most indifferent dinner. A " science'' based 

 on probabilities may turn out to be a new system founded on 

 contradictions. 



Prof. Herdman, in speaking of the colours of Nudibranchs 

 and their probably protective character, forcibly observes that we 

 cannot gauge the problem by observing the animals in a museum- 

 jar, or as illustrated in a book, or on the wall. " In order to 

 interpret correctly the effect of their form and colours, we must 

 see them alive and at home, and we must experiment upon their 

 edibility or otherwise in the tanks of our biological stations." J 

 Such a course would doubtless give many positive and many 

 negative results, confirming in many cases the theory — if it is 

 still to called but a theory — of mimicry, and preventing many 

 hasty and erroneous conclusions in other cases, where mimicry 

 is only a suggestion, and much discredit is brought to the argu- 

 ment. The " law of evidence " might with advantage be studied 



* Guppy, ' The Solomon Islands,' p. 316. — Hylodes martinicensis affords 

 another instance (cf. Mon. Berl. Ac. 1876, p. 714). 



f ' The Whence and the Whither of Man,' p. 164.— It is only fair to add 

 that this is a book written by an American Professor of Biology, consisting 

 of a series of Morse Lectures delivered at a " Union Theological Seminary," 

 on the agreement that the subject of the lectures was to have to do with 

 11 The relation of the Bible to any of the Sciences." 



I Opening Address, Sect. Zoology, Brit. Assoc. Ipswich, 1895. 



