

TOWER, DARWINISM. 423 
The general results from 220 censuses on ten plots scattered 
Over about five miles of the valley of the Rio Motzorongo, showed 
that of all the Lepidoptera, which included both day and night 
flying types of about five hundred species, less than one per cent 
of the total could be attributed to elimination by vertebrate enemies 
(0.967 0/9). Of the models and mimics, which were all of them 
_day fliers, the mass figures of those killed by vertebrates were, 
for models 0.4890/,; and for mimics, 0.5090/,. The chief elimina- 
tors were spiders, ants and dragon-flies, in the order mentioned, 
whose combined efforts eliminated — 99.59/) of those found dead. 
In the 220 censuses from the ten plots, 2.219.754 pairs of wings 
were recovered during the eight years of observation. Among 
them were 891 pairs of wings from the models and 973 of the 
mimics. 
These results from different locations in the same general area 
of untouched tropical rain-forest, where conditions were operating, 
as far as could be determined, in a perfectly natural, ordinary 
manner, showed that the eliminating effect supposed to exist with 
reference to these models and mimics is substantially 0.50 °/o, 
affecting both practically alike. There was not the difference in 
either numbers or percentages between the models and mimics 
eliminated that, a priori, we should expect to find if the selective 
capacity of vertebrate enemies actually existed. It must be remem- 
bered also that this 0.50 °/) eliminated by vertebrate enemies 
represents 0.509/) of the individuals of that generation reaching 
adult condition, so that the total selective effect by the predacious 
vertebrate enemies upon a generation is extremely small. 
It may be contended that the findings are not relative to the 
problem because it may be alleged, as some enthusiastic Neo- 
Darwinians have done, that since the mimetic state has attained 
its supposedly perfected condition, selective elimination is no 
longer operative. It is difficult to understand how it happens that 
in the unknown past, birds and other vertebrate enemies exercised 
discriminating powers between the edible and the non-edible, but 
are not doing it, apparently, at the location where these obser- 
vations were made. I shall not be surprised if some expert mimeti- 
