491 



JOURNAL OF HORTICULTURE AND COTTAGE GARDENER. 



[ December 22, 1870. 



on the 7th inst., and unless more severe weather sets in he is 

 confident of being able to do so at Christmas. 



MIMETIC ANALOGY. 



The following is an extract from notes read by Mr. Murray 

 at the last meeting of the Scientific Committee of the Royal 

 Horticultural Society. 



''Although, mimicry occurs between various tribes or genera, it has 

 been observed most frequently in connection with the most common 

 species of the country. This is what would naturally be the case with 

 hybridisation, supposing all to start fair, and to be equally liable to 

 hybridisation. But this is an assumption which we are scarcely war- 

 ranted in making, and I therefore do not press this inference further 

 than as of some conditional value. 



" After the second generation of hybrids, those which do not revert 

 to the type break out into an overflow of irregular variation, which 

 supplies many of his most remarkable sports to the horticulturist, and 

 many of his most puzzling difficulties to the systematic botanist. On 

 the assumption that the mimicry in question is the result of hybridi- 

 sation, we should therefore expect to find a marked degree of variation 

 among the mimicking species. And so we do." 



Mr. Murray cited evidence on thishead, and then continued: — 

 " It seems a fair inference that when the mimicking species are not 

 variable, ihey have been established before the second generation of 

 hybrids, and where they are variable th^y have been established subse- 

 quent to the second generation, and have experienced the usual shock 

 to stability occasioned by such repeated loosenings of the fetters of 

 .specific identity. 



"Mr. Bates' list of mimic3 and mimicked species shows, too, that 

 when a species is mimicked by one species or genus it ia often mimicked 

 by more — a fact which, applied to the idea of hybridisation, simply 

 means that that species had a readiness to take to itself wives of more 

 than one of the nations round about. It is only what we find in 

 plants — that some are more open to hybridisation than others, or per- 

 haps analogous to our moral experience, that where scope is allowed to 

 our own passions, license soon degenerates into libertinism. 



" Another feature familiar to all hjbridisera occurs in these mimic- 

 ries. Notwithstanding the statement of Whicura to the contrary, it 

 is now perfectly well known that in attempting to obtain a cross be- 

 tween two species, we often fail when we work with the male of one 

 species and the female of another, while we succeed when we reverse 

 the process, and take the male of the latter and the female of the former. 

 In plants, the cases where this capability of crossing in only one 

 direction oceurB are beyond numbering. Mr. Isaac Anderson-Henry 

 cites many of them in. his late Presidential address to the Botanic 

 Society of Edinburgh, and in the paper which I have now the pleasure 

 to lay before the meeting. The very same thiug has occurred with 

 the mimicries recorded by Mr. Bates. They are all on one side of the 

 house. The case which so often occurs in plants has obviously occurred 

 among the butterflies. The cross has taken only from one side — which 

 is it ? Judging from the example of the mnle it should be on the side 

 of highest organisation; that is, that the male parent has been of the 

 lower organisation, and the female parent (the actual bringer-forth) 

 of the higher. Now, which is the side of highest organisation in the 

 Danaids and Pieridre — is it that of greatest strength ? If it were so, 

 it would then be the Danaids, for they are larger, finer, and more 

 powerful than the more northern whites. But organisation is a higher 

 test than mere strength, and an advance in it is doubtless what must 

 he the unconscious aim of the ambitious match-seeker. This, too, 

 seems to be on the side of the Brazilian tribe. Mr. Bates so considers 

 it, and his reason is that the essential quality of butterflies being 

 flight, the type which has most attention paid to its wings and least to 

 its legs must be highest of its order. Others think differently, and say 

 that a type which has had two of its limbs (its fore legs) almost atrophied 

 cannot be so perfect an animal as one which has them all in perfection. 

 But I agree with Mr. Bates on this point (at all events in his conclu- 

 sion). The greater number of legs cannot be any indication of higher 

 organisation, or a centipede might dispute supremacy with ourselves, 

 and push us from our stools. The fewer limbs, that is, the simpler the 

 apparatus that a creature can do its work with, the higher the perfec- 

 tion of the machine. Therefore, doubtless, the cross from which these 

 mimics resulted was one by the maleB of the whites upon the females 

 of the Danaids. 



"Now what does plant-hybridisation tell us on this point? "What 

 does Mr. Henry say ? I regret to differ from so great an authority as 

 "Wichura (who had maintained that 'the products which arise from 

 reciprocal crossing in plants, unlike those which are formed among 

 animals, are perfectly alike'), and must venture to demur to the doc- 

 trine in more decided terms than Mr. Berkeley has done. I have had 

 so many instances of hybrids taking sometimes to one side and some- 

 times to another — hut most frequently to that of the mother — that to 

 those who, like me, have tried their hand with many genera, it would be 

 a matter of supererogation to give instances. I have had them by the 

 score." 



" But the mixed product also corresponds with another fact observed 

 in hybridisation. Mr. Henry informs me that in some of his crossings 

 of plants he has only succeeded in altering the flower, the foliage 

 continuing persist the same as that of one of the parents. He 



has not succeeded in distributing the union through all parts. That 

 is exactly parallel to what we see in these mimicries. In plants it 

 may be a question whether we should consider the flower or the foliage 

 as the more structural parts ; for my part I should take the flower as 

 the more important, and therefore equivalent to the structure of the 

 legs and wings, and the foliage and habit of the plant as equivalent to 

 the colour and form of the wings, and general appearance of the insect. 

 In Mr. Anderson-Henry's case another phase of the mimicry, which 

 I have no doubt will be found to have also its parallel in the hybridi- 

 sation of plants, although I am not able to cite any instances exactly 

 in point, is, that in species which have dissimilar sexes it sometimes 

 extends to both sexes, the males being like the males and the females 

 like the females, but in other instances is confined to the females. _ I 

 believe that the reason why I have no case in point to cite in plants is, 

 that it can only be had in dicecious plants ; and the hybridisation of 

 dioecious plants has hitherto been scarcely at all attended to. Mr. 

 Henry has some coming forward, but they have not yet flowered. 



" The last point to be noticed is one of some importance, as being 

 the only one furnishing a shadow of objection to the explanation of 

 the mimicries in question by hybridisation. It is, that the nearest 

 natural allies of both the mimickers and mimicked are not always to 

 be found in the same district as them. This deserves the more atten- 

 tion, that it appeared so strong to Mr. Bates as to lead him to relin- 

 quish the idea of hybridisation as an explanation after it had crossed 

 his mind. 



"Before I proceed to show how simple the explanation of the absence 

 of one of the parents is, I must beg to note, in passing, the admission 

 that there are distinct forms whose intercrossing would produce the 

 hybrids. That granted, I would remind the reader of what Mr. Bates 

 has obviously overlooked, that we are dealing with a phenomenon, 

 probably of a very ancient date, and that one side of the parental 

 stock may have disappeared in the course of time. One of the parents 

 we know to be present (the so-called mimicked), but there are excellent 

 reasons, based on climatal considerations, why the other parent should 

 not he present. 



" There is yet another phenomenon connected with mimicry, which 

 possibly may also be connected with hybridisation— viz., the occurrence 

 of what Mr. Wallace has called dimorphism in insects among the 

 mimicking or mimicked species. "We must not, however, confound this 

 dimorphism with Darwiu's dimorphism in plants. The two are totally 

 different things, and, as it seems to me, have no relation or analogy to 

 each other. In plants the dimorphism is always confined to the repro- 

 ductive organs, in insects it has apparently nothing to do with them. 

 Moreover, it seems to me that all the instances of so-called dimorphism 

 in insects that have yet been recorded are nothing but examples of 

 variation, perhaps complicated by hybridisation." 



ENTOMOLOGICAL SOCIETY'S MEETING. 



The second meeting of the present season was held on the 21st of 

 November, the President, A. R. Wallace, Esq., in the chair. Amongst 

 the donations to the Society's library were the publications of the 

 Entomological Societies of St. Petersburgh and Italy, the Royal Society 

 of London ; and a memoir on the cultivation of silk m the Australian 

 Colonies by Captain Hutton, published at Calcutta during the present 



J6 Mr. F. Bond exhibited Fumea reticella, male and female, the latter 

 distinguished by the absence of wool on the terminal segment of the 

 body ■ also Aei'dalia strigaria and Phycis obductella, all taken near 

 Gravesend by Mr. Button. Mr. Albert Miiller exhibited a specimen 

 of the large fleshy larva of the Longicorn Beetle, ^gosoma scabn- 

 corne, which infests the trunks of Lime trees in the great square or 

 Basle in Switzerland. Mr. Frederick Smith sent a number of speci- 

 mens of a small dipterous insect, Phora florea, the larvre ot which 

 infest the interior of the bodies of the larva and pupa of the common 

 Wasp as many as fourteen having been found in a single Wasp-grub ; 

 and out of a comb of 200 or 300 cells, only a few Wasps escaped the 

 attacks of this little insidious fly. _ 



Mr Butler read a memoir containing descriptions ot new exotic 

 species of Butterflies of the families Nymphalids and Hesperudm in 

 the collection of the British Museum from Venezuela, and m Mr. 

 Dawe's collection from the Eaden Museum. 



Mr F Bond stated that at the late exhibition of the Haggerstone 

 Entomological Society he had observed a singular specimen of Vanessa 

 Atalanta haviog the head of the larva remaining upon and concealing 

 the head of the Butterfly ; also a curious specimen of the common 

 Brimstone Butterfly, having the wings streaked with the colours ot the 



° P profe e ssor Westwood stated that he had recently reared a number of 

 specimens of Phloiotribus Olere from the stem of an Ash tree imported 

 from France. It had hitherto only been reared from the Olive tree in 

 the south of France. 



BEECH FOR CHALKY SOIL. 



Will you permit me to say that you are perfectly correct in 

 recommending to your correspondent to plant Beech trees in a 

 chalky soil? I am at present residing in a locality where there 

 is nothing but chalk, and the Beech trees grow magnificently ; 



