NA TURE 



[November 4, 1897 



parts the author admits the existence of large groups 

 in which both sexes are equally mimetic. Again, his 

 frequently-stated dictum, that mimicry begins with the 

 female, is controverted by the subsequent admission that 

 he is unable to offer any sufficient proofs of it in some 

 of the most important groups. 



The author has the most extraordinarily exaggerated 

 notions of the importance of his own contributions to the 

 subject, and he frequently speaks as if he were one of its 

 pioneers, and, with cool assurance, ranges himself beside 

 Bates and Wallace, or more frequently himself claims 

 the credit for work which they had long before accom- 

 plished. Thus, on p. 93 he speaks of 



"the fact which I have so firmly established, viz. that 

 all mimetic modifications appear first in the female^ this 

 sex being so much ntore important than the male for the 

 preservation of the species." 



In the first place, this principle is by no means firmly 

 established as of universal occurrence ; in the second, all 

 that is really true in the statement was brought forward 

 long ago by Wallace. Again, on p. loo he states with 

 all the insistence of spaced type : 



" Through my observations in Siam I have arrived at 

 the general conclusion that those larvae which conceal 

 themselves most carefully or show the most perfect 

 protective adaptation are probably those most sought 

 by their enemies on account of their especial edible 

 qualities." 



By this unjustifiable or, accepting the most favourable 

 interpretation, ignorant claim to a principle enunciated 

 many years ago by Wallace, Haase puts in a most un- 

 favourable light the really useful work which he has done 

 in the comparatively humble position of a supporter of a 

 well-established and thoroughly accepted conclusion. 



Again, on p. 123 he calmly appropriates a principle 

 which we owe to Bates : 



' "Thus, we find in these cases also a confirmation of 

 our principle that it is always the rarer immune species 

 which mimics the more common form in order to escape 

 pursuit in its swarms." 



The examples quoted above sink, however, into insig- 

 nificance beside the passage which opens the section 

 "Objections to the Theory of Mimicry" on p. 123 : 

 " The attacks on the hypothesis held by Bates, Wallace 

 and myself, viz. that mimicry is the result of natural 

 selection, &c." Having gone so far, Haase was no 

 doubt astonished at his own self-effacement in thus 

 placing his name after the distinguished naturalists to 

 whom we are really indebted for something more than a 

 patient accumulation of facts. Others will, however, feel 



.that it is a piece of sheer impudence for Haase thus to 

 range his name beside the pioneers of the subject to 

 the exclusion of their true compeers Fritz Miiller and 

 Roland Trimen. 



For a keen naturalist possessing a wide acquaintance 



, with insect form and insect life, Haase shows a strange 

 want of grasp of the well-known principles which operate 

 among living beings in the natural state. Thus he 

 continually speaks as if the protective qualities which 

 accompany a warning appearance confer absolute im- 



. munity — an immunity as complete for the larva against 



,-the attacks of parasites as for the imago against insect- 

 eating enemies. The term " immunity " ought not to 

 NO. 1462, VOL 57] 



be used at all with regard to these forms, unless- 

 very carefully qualified. Such a heading as that on 

 p. 96, " Origin of Mimicry between Non-immune and 

 Immune Lepidoptera," is hable to convey a very false 

 impression of the facts of nature. We may feel con- 

 fident that the average ratio of extinction to survival is 

 the same in both groups — that a pair of the so-called 

 immune species, in spite of all their numerous progeny, 

 are upon the average succeeded by a pair only. The 

 warning colours and the qualities they imply do indeed 

 secure a high degree of immunity from the attacks of 

 certain enemies, especially during certain stages, but 

 other enemies have acquired the hardihood necessary to- 

 make use of the abundant and easily captured prey. So 

 far from accepting Haase's dictum (p. 97) that 



'it is certain that the early stages of immune butterflies 

 suffer in general less from parasites than those of other 

 Lepidoptera," 



we may feel confident that the reverse is the truth. 

 Haase brings before ys an unworkable theory according 

 to which the species with warning colours must continue 

 to increase in numbers, indefinitely from generation to 

 generation. No doubt at the very origin of this special 

 means of defence the species concerned were enabled to 

 increase largely in numbers, and very many of them 

 have reached a condition of equilibrium as abundant 

 and dominant species. But as soon as this equilibrium 

 is reached there is no interference in the general law 

 that the amount of extinction keeps down the numbers 

 of the species to a certain average ; and we may there- 

 fore feel sure that the relative immunity from the attacks 

 of certain enemies, and during certain stages, is com- 

 pensated by the excessive attacks of other enemies, and 

 during other stages ; and furthermore, that during the 

 progressive growth of the numbers of the species, each 

 increase was attended by increased attacks until equi- 

 librium was reached. Haase depicts a state of affairs 

 which would cause an indefinite increase, and could lead 

 to nothing but the extinction of the food-plant, and 

 consequently the disappearance of the species, The 

 keen observation of Belt detected some of the ways in 

 which the numbers of unpalatable butterflies are kept 

 down ; for he noticed a flower-haunting spider which 

 eagerly devoured them, and a wasp which stored them 

 up in its nest. In order to support his views of extreme 

 immunity, Haase makes, as regards these observations 

 of Belt, the absurd suggestion that "it is perhaps possible 

 that the mimic was mistaken for the model." 



Haase shows a similar want of insight in his contention 

 that mimicry and protective resemblance arose in a. 

 time of great struggle which has now ceased to exist. He 

 concludes his work in these words : 



"It is probable that all these resemblances to the 

 moving or motionless and the living or lifeless environ- 

 ment have arisen in the interest of the preservation of the 

 species from extinction during periods when the struggle 

 for existence was most bitter, and from chance variations 

 which corresponded to this purpose and whose further 

 development was aided by natural selection and fixed by 

 inheritance. Under these circumstances it appears then, 

 to close with the apt words of Brauer, that ' the struggle 

 for existence being ended, the forms reach a state of 

 equilibrium, and the living species (being under the same 

 conditions) are preserved from extinction.' " 



