Mimetic Attraction. 323 
the expense of other individuals of the same species, some 
of which must necessarily fall victims to their insectivorous 
enemies during the “ education” of the latter as to the 
kinds of prey to be sought or avoided. Hach form that 
thus succeeds in establishing itself becomes, in propor- 
tion to its nauseous character and the ease with which it 
can be recognised, a centre of attraction for other species, 
which, by assimilating their own aspect to that of their 
model, are enabled to share in the immunity from attack 
enjoyed by the latter. It is now considered probable by 
many that this power of attraction is exercised by 
dominant inedible species over edible and inedible forms 
alike; there is, however, one important difference be- 
tween the two cases, which I have before endeavoured to 
point out, but which seems to need a more explicit state- 
ment than has yet been given to it. 
Let us first take the case of a species which is edible, 
and therefore liable to extermination by insectivorous 
animals. The chances of the survival of such a species 
depend on the excellence of its means of defence ; such as 
superior swiftness, or the power of concealment, whether 
by resemblance to inanimate objects, or to some other 
species protected by a disagreeable flavour. The force 
which impels an edible species to seek protection by the 
last-named method, viz., by sheltering itself under the 
reputation of a conspicuous inedible form, is the well- 
known “ Batesian mimicry.” With reference to this, 
which is the most complete kind of mimicry, it is to be 
observed that the advantage of association is all on the 
side of the mimic, and is not shared in the least degree by 
the model. Indeed, the existence of the edible mimicking 
species is a source of danger to the form mimicked, 
inasmuch as any experience gained by tasting the former 
would be used to the detriment of the latter. From these 
considerations two consequences follow; the first being 
that such an association can subsist only when the 
numbers of the mimic are insignificant compared with 
those of the model, for otherwise the latter’s reputation 
for inedibility would be interfered with, and eventually 
destroyed. ‘The second consequence is that the attrac- 
tive force leading to assimilation between the two forms 
can act only in one direction; 7.e., the model attracts the 
mimic, but the mimic can exert no reciprocal influence 
upon the model. ‘The latter stands secure upon its own 
