878 ) 
striking superficial similarity between forms belonging to widely 
different groups, can hardly fail to provide certain advantages in 
the strugele for existence either to one or to both of them, or at least 
must have done so in former periods of their occurrence on earth. 
I shall henceforth restrict myself to a careful comparative analysis 
of the colour-pattern. But before entering on this task, T wish to 
remark that the phenomenon of mimetic resemblance can never be 
ascribed to the influence of a general law, and consequently the 
different cases of Mimiery must be judged separately, quite independently 
of each other That e.g. a Sesia resembles a wasp, cannot possibly 
stand in any genetic connection to the mimetic similarity between 
a Dismorphia and an Ithomiid or a Heliconid, or between a set of 
species of the latter families amongst each other. Nor can this 
occurrence of wasp-like Sphingids stand in any relation to the existence 
of other members of that same group, which seem to have assumed 
the habitus of humble- bees. 
Mimetie resemblances consequently must be considered as of casual 
origin, and the considerable number of conditions, which had to be 
fulfilled before a real case of Mimicry could enter into existence, 
make us readily understand the relative rareness of the phenomenon, 
and its apparently capricious distribution over the animal kingdom 
(as Reset has so judiciously pointed out). 
Though, as mentioned before, I am inclined to acknowledge the 
high probability, that in many cases the close superficial and simulating 
resemblance existing between mimic and model is extremely useful 
either to the mimic only or to all the members of the mimetic set, 
I am also convinced that no impartial judgment can possibly be 
formed without carefully abstaining from all considerations about this 
hypothetical and problematic usefulness, and exclusively regarding 
the mimetic forms from a purely morphological standpoint, that is 
to say investigating them according to the very same principles and 
rules that have proved useful for the understanding of the colour- 
pattern of insects in general, and the laws that we could deduce 
from this study. To this conclusion we are logically led by the 
observation, that mimetic patterns do not differ in any special feature 
from colour-designs in general, but on the contrary agree with the 
non-mimetie patterns, at least when these are embraced in a general 
view. Solely when we compare the mimetic forms with their nearest 
allies: the non-mimetic members of the same genera, do we meet 
with certain cases where they seem to depart widely from the 
common generic type, though even this by no means can be called 
the general rule. By the adherents of the Mimicry-hypothesis this 
