
Dec, 22 1870| 
NATURE 
155 

individuals, swarms of each kind being found in the localities | 
they inhabit. The Leptalidz (mimics) are exceedingly rare ; 
they cannot be more than 1 inr,000 with regard to the Jthomiz.” 
This is quite what we should expect if the resemblance is due to 
hybridisation. Hybridisation is not the normal mode of pro- 
ducing either species or individuals. It is not the plan laid down 
by Nature. Being exceptional, it is, of course, comparatively 
rare. But there is no reason for rarity if it be the result of 
Natural Selection. That operation is going on equally upon all, 
and under that hypothesis mimicry is just as powerful an influence 
in modifying and producing forms as any other; and there is no | 
reason whatever why it should have less conspicuous results ; 
indeed, it should have more, if we judge by the long-continued 
persistence of influence which must have been in operation to 
produce such exact resemblances, and which, indeed, seems very 
much thrown away when confined to the I ina 1,000 mentioned 
by Mr. Bates. 
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 wou!d 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 warranted in making, and I therefore do 
not press this inference further than as of some conditional 
value. s 
After the second generation of hybrids in plants, it was 
first shown by M. Naudin, and is now well known to all 
hybridisers, that those which do not revert to 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 qvestion 
is the result of hybridisation, we should therefore expect 
to find a marked degree of variation among the mimicking 
species. Andsowedo. Mr. Bates figures no Jess than fifteen 
varieties of Leplalis Jihomie, one of his mimics, which itself 
mimics seven different species (all very close to each other, 
however, and pe:haps scarcely deserving the name of inde- 
pendent instances.) Mr. Trimen figures six varieties of 2epilio 
Merope, which supplies four of his instances of mimicry, and Mr, 
Wallace’s imitating Papilios were in like manner remarkable 
for their variations. It seems a fair inference that when the 
mimicking species are not variable they have been established 
before the second generation of hybrids, and where they are 
variable they have been established subsequent to the second 
generation, and have experienced the usual shock to stability 
occasioned by such repeated loosening of the fetters of specific 
identity. 
Mr. Bates’s list of mimics and mimicked species shows, too, 
that when a species is mimicked by one species or genus it is 
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. 
Out of twenty-eight Danaoid species cited by him, which had 
been mimicked or had families from strange husbands, fourteen 
had families from one each, three from two each, and six from 
three each. It is only what we find in plants, that some are 
more open to hybridisation than others ; or perhaps, analogous 
to our moral experience, that where scope is allowed to our 
own passions, license soon degenerates into libertinism, 
Another feature, familiar to all hybridisers, occurs in these 
mimicries. Notwithstanding the statement of Wichura to the 
contrary, it is now perfectly well known that in attempting to 
obtain a cross between two species we often fail when we work 
with the male of one species and the female of the other, 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 occurs are beyond num- 
ber. Mr. Isaac Anderson Henry cites many of them in his late 
Presidential Address to the Botanical Society of Edinburgh, and in 
the paper which I have now the pleasure to lay before the Commit- 
tee. The very same thing has occurred with the mimicries recorded 
by Mr. Bates. They are all on one side of the house. According 
to my view (indeed if hybridisation is once allowed to have been 
the motive power, it must be according to every one’s view), the 
parents were the Danaids on the one side, and the cabbage 
whites (Pieridae) on the other, for all the mimicked are Danaids 
with their special characters, viz., only four apparent legs, while 
all the mimickers, like the whites, have their special characters, 
| dispute supremacy with ourselves, 


‘six legs apparent, If they had been hybridised from both sides, 
we should have had some Danaids with the form and colour of 
the whites, as well as whites with the form and colour of Danaids: 
but we have not. The case which so often occursin plants has 
obviously occurred here. The cross was taken only from one 
side. Which is it? I apprehend, from other examples, that it 
sheuld 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 Pieridae? 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 t!ie more 
northern whites. But organisation is a higher test than mere 
strength. This, too, seems to be on the side of the Brazilian 
tribe. Mr. Bates so considers it, and his reason is that, the essen- 
tial 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 anterior legs) almost atrophied, 
cannot be so perfect an animal as one which has them all in 
perfection. But Iagree with Mr. Bates on this point (at all 
events in his conclusion). The greater number of legs cannot 
be any indication of higher organisation, or a centipede might 
and push us from our stools. 
Multiplicity of sub-division or repetition of parts is acknowledged 
by all physiologists to be an indicatior on inferiority of organisa- 
tion. The fewer limbs, that is the simpler the apparatus that 
a creature can do its work with, the higher the perfection of the 
machine. ‘Therefore, doubtless, Brazilian Danaids are the higher 
type, and if (as I believe to be the case). in crosses of difficult 
accomplishment, the female is the higher parent, then the cross 
from which these mimics resulted was one by the males of the 
whites upon the females of the Danaids. 
In what I have above said as to one-sided crossing, I have 
assumed that in plant-hybridisation the fact would be admittcd ; 
but as it is in contradiction to the statement of so eminent an 
authority as Wichura, I shall remove all doubt from the subject 
by quoting Mr. Anderson Henry. Wesays :—‘‘T regret to difter 
from so great an authority as Wichura (who has 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 docirine in more decided terms 
than Mr. Berkeley does. I have had so many instances of 
hybrids taking sometimes to one side and sometimes to another, 
but most frequently to that of the mother, that to those who, like 
me, have tried their hand with many genera, it would bea 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 
flowers, the foliage continuing persistently 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. The number of legs and the nervation 
of the wings (in other words the more structural portions of the 
animal) remain special as in one parent, while the colour and 
form of the wings, &c., is taken from the other. In the butter- 
flies it is the more structural parts (legs, nervures of wings, &c.) 
of the male parent which are observed in the offspring, while the 
form and general appearance only of the female parent is adopted. 
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 in Mr, Anderson Henry’s case as equiva- 
lent to the colour and form of the wings and general appear- 
ance of the insect. Another phase of the mimicry, which I 
have no doubt will be found to have also its parallel in the hybri- 
disation 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 dic- 
cious plants, and the hybridisation of dicecious 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 expla- 
nation of the mimicries in question by hybridisation. It is that 
