The Making of Species 
by the same species” (Essays on Evolutzon, 
Pp. 372). 
Occasionally the female mimics two other 
species, z.e. she occurs in two forms, each like 
a different species. 
It sometimes happens that the female alone 
mimics. This is said by Wallace to be due to 
her greater need of protection. When she is 
laden with eggs her flightiis slow, and therefore 
she requires a special degree of protection. 
g. It is said that in some species we find a 
non-mimetic ancestor preserved on islands where 
the struggle for existence is less severe, while 
on the adjacent continent mimicry has been 
developed. 
10. It is alleged that in the cases where moths 
resemble butterflies the former are either as 
diurnal as the butterflies or are species which 
“readily fly by day when disturbed.” 
11. It is asserted that some seasonally di- 
morphic forms are examples of mimicry only in 
one state, in the form that comes into being at 
the time when the struggle for existence is most 
severe; that is to say, in the dry season, in 
Africa, when insect life is far less abundant than 
in the rainy season. 
In other cases the mimicry of the dry-weather 
form is said to be far more perfect. 
Instances of this phenomenon are set forth in 
Professor Poulton’s Essays on Evolution. 
230 
