February 24, 1898J 



NA rURE 



389 



LETTERS TO THE EDITOR 



[The Editor does not hold himself responsible for opinions ex- 

 pressed by his correspondents. Neither can he undeitake 

 to return, or to correspond with the writers of, rejected 

 manuscripts intended for this or any other part of Naturp:. 

 No notice is taken of anonymous commun'cationsJ\ 



Protective Mimicry and Common Warning Colours. 



I HAVE just read with interest Sir George Hampson's 

 criticism of certain supposed examples of protective mimicry. 

 Such outspoken attacks are satisfactory in bringing out the 

 truth one way or the other ; and they contrast very favourably 

 with vague expressions of opposition unaccompanied by reasons, 

 and not stated in a manner or on an occasion which would 

 permit reply. 



I find from his letter that insufficiently supported conclusions 

 are not confined to those who accept the theories in question. 

 Sir George Hampson described a new geometer {Abraxas 

 etridoides) from a single specimen in a private collection, and 

 pointed out its resemblance to a Teracolus {T. etrida) from the 

 same part of the world. Colonel Swinhoe directed the attention 

 of the President of the Entomological Society to the resemblance, 

 considering that it supported his (the Colonel's) contention that 

 Teracolus is a protected genus. From these facts Sir George 

 Hampson draws the remarkable conclusion that Colonel Swinhoe 

 had in all probability never seen the species of Abraxas referred 

 to. I give the inference in his own words — " this was quite 

 enough for such an ardent student of mimicry as Colonel Swinhoe 

 to base the statement on, without knowing any more of the 

 species, and probably without ever having seen it, the type being 

 in a private collection." The last reason would be more con- 

 vincing if it was not followed by the statement — " I have, 

 however, lately received more specimens." If Sir George 

 Hampson, why not Colonel Swinhoe? As a matter of fact. 

 Colonel Swinhoe received several specimens of Abraxas 

 etridoides many months before he wrote to the President about 

 them. There is a specimen in the Hope Collection here, pre- 

 sented by him in the early summer of last year. 



All this does not afifect the theory of mimicry. But the letter 

 goes on to argue that the resemblance cannot be mimetic because 

 the Abraxas rests in damp woods, while the Tercuolus is flying 

 on the plains 6000 feet below ; and, furthermore, that the former 

 is protected by distastefulness, while the latter is not. Similar 

 objections are then raised against the supposed mimetic re- 

 semblance of Chalcosid moths to Danaine and Papilionine 

 butterflies. 



Now I quite agree that these criticisms, and especially that of 

 the special protection of the moths, are destructive of any 

 interpretation of the resemblance based on Bates' theory of 

 protective mimicry. But they do not similarly aff"ect that 

 theory of mimicry (or more accurately common warning [syn- 

 aposemalic] colours) which we owe to Fritz Muller. Being 

 aware of the distasteful qualities of Abraxas, I had at once 

 placed the example under the latter category and not under the 

 former. 



The Miillerian theory supposes that a common type of 

 appearance among distasteful insects in the same locality acts as 

 a common advertisement to enemies, so that the loss 'of life 

 which must ensue during the time in which each generation of J 

 enemies is being educated to avoid the owners of a particular 

 type of pattern and colouring, is shared between these species 

 instead of being borne by each of them independently. 



Prof. Lloyd Morgan's recent experiments on young birds of 

 many species prove that there is no inherited knowledge of 

 suitability or unsuitability for food, but that everything of an 

 appropriate size and at the right distance is pecked at and 

 tested. On the other hand the young birds are extremely quick 

 in learning, and have very retentive memories. Furthermore 

 one unpleasant experience makes them suspicious of other things, 

 and they remember well the appearance of the insect which gave 

 them a disagreeable surprise. Many more such experiments 

 are needed, but taken alone they go far to show that the educa- 

 tion of young birds is actually of the kind which is presupposed 

 by Fritz Miiller's theory. 



And what is true of birds is probably true of other animals 

 as well. My experience with lizards points in the same 

 direction. 



Sir George Hampson has previously pointed out that birds 

 sometimes devour TeracoH ; but I have induced a lizard, by 



NO. 1478, VOL. 57] 



hunger, to eat an Abraxas. It is probable that Teracoli are, on 

 the whole, avoided by birds ; and if this is also true of the 

 Abraxas, the resemblance may well be advantageous in spite of 

 the difi"erence in habits and the difference of station, even 

 granting that the " good round sum " of 6000 feet is an absolute 

 barrier to the Teracoli below and the Abiaxas above. But 

 fuiure investigation may show that they approach much nearer 

 than this. 



The facts brought forward in Sir George Hampson's letter, 

 while, I submit, by no means fatal to the Miillerian theory of 

 mimicry, seem to be entirely destructive of the other suggestions 

 by which the attempt has been made to explain these resem- 

 blances — suggestions which depend upon similarity in climatic 

 or other physical or chemical conditions connected with locality 

 The last paragraph of the letter demands a word of protest. 

 If insufficient field observations have been made, it is because the 

 observers have thought of other things, and chiefly the amassing 

 of specimens ; but it is. in part, due to the extreme difficulty of 

 the observations themselves. And under any circumstances the 

 museum work was necessary for the theory. Mr. Godman, in 

 his presidential address to the Entomological Society, told us 

 that the theory was suggested to Bates as a result of the com- 

 parison of specimens at home, although of course his memory of 

 observations in the field was also necessary. The work in the 

 study enabled him to bring under observation at a single time 

 the captures which were separated by great intervals of time and 

 space ; and no doubt it was the opportunity thus afforded of 

 taking a broad view of the resemblances as a whole, which 

 enabled him to originate the theory. 



It seems strange that a writer whose energetic and successful 

 work has involved so much "matching of specimens in a 

 drawer," should speak of mimicry as "degraded " by such study. 

 It is a necessary and important study for the naming of species 

 as well as the recognition of examples of mimicry, and as such 

 it deserves respectful attention, although it may at times have 

 led to the creation of "museum-made" species on an even 

 larger scale than the manufacture of " museum- made mimicry." 

 The matching of ribbons of uniform colour can hardly be 

 compared with any degree of fairness to the matching of the 

 complex patterns on the wings of Lepidoptera ; but in the 

 matching of highly developed specimens of decorative art by the 

 anthropologist, and in the attempt to determine whether the 

 resemblance is due to a common origin, or to accident, or to the 

 mind of man working independently along the same lines, we 

 have problems which present much in common with those 

 confronting the student of mimicry. 



In conclusion it may be well to remind those who oppose the 

 theories of mimicry on the ground that the evidence is not 

 demonstrative, that we believe in evolution although we do not 

 see one species growing into another. We believe the theories 

 of mimicry and of common warning colours, not because we 

 have before us demonstrative proof in a complete knowledge 

 of the details of the struggle for existence —it will be very long 

 before we attain to this — but for the same reason that we 

 believe in evolution — because the theory offers an intelligible 

 explanation of a vast number of facts which are unexplained by 

 any other theory as yet brought forward, and especially because 

 it enables us to predict the existence of facts which we can 

 afterwards verify. Edward B. Poulton. 



Oxford, February 18. 



Oat Smut as an Artist's Pigment. 



With reference to Mr. David Paterson's interesting letter 

 in Nature for February 17 (p. 364), it may be noted that a 

 copy of an etching from a painting by Berghem, in the Kew 

 Museum, No. 2 (Case 115, No. 200), is drawn with smut of 

 wheat [Ustilago Tritici), and that, according to Dietel {Die 

 Naturlichen Pflanzenfamilien, Th. I. I Abth. p. 6), ladies in 

 Japan are accustomed to use the dark olive- brown spores of 

 Ustilago esculenta as a pigment for painting the eyebrows. 



H. Marshall Ward. 



Botanical Laboratory, Cambridge, February 18. 



Giraffe from the Niger Territories. 



My brother, the late Lieut. R. H. McCorquodale, of the 

 3rd Dragoon Guards, while doing special service duty in West 

 Africa, was fortunate enough to kill a very fine giraffe (female). 

 This is a most interesting record, as it is the only specimen 



