436 QUEENSLAND AGRICULTURAL JOURNAL. [1 June, 1899. 
plants and animals, and a comparatively small number of them survived—that 
is, those whose constitutions were fit to bear the changes of living to which they 
were now exposed. Not alone their own bodies, but much more those of their: 
offspring, conceived and born when those changes took place, adapted themselves: 
to the new conditions. Some alterations took place in their internal constitu- 
tion as well as in their outer appearance. The results of geological researches 
have proved to us that changes like that have taken place at different periods, 
and this does not only account to a considerable extent for a great variety of 
form, but also for many a link in the chain of suecession from lower to higher 
forms of development having been lost.. 
The present variety and perfection of animals can also be accounted for: 
through the struggle for existence which pervades the whole vegetable and 
animal kingdom. We may convince ourselves every day that stronger and more 
perfect beings get the better of inferior ones, drive them as it were out of the 
field, deprive them of their means of existence, and are the instruments of 
their extinction, whilst the stronger ones, and the strongest again of their 
progeny, continue to exist and propagate. 
A naturalist, travelling in Africa, observed how a small tribe of monkeys was. 
completely tyrannised over by one male who happened to be stronger and 
bigger than the others. Whenever any other male attempted to approach a 
female, the big monkey attacked and punished him severely. Should the old. 
monkey continue to live, the tribe would after a time be composed of his own 
offspring only. In such a case, the sire will cover his daughters, grand- 
daughters, &c., until a son, stronger than himself, will beat him out of the field,. 
exercise a similar tyranny, and run with females that are closely related to him. 
We have here not only a case of the best male surviving, but also an instance 
of in-and-in breeding, as practised by nature, with the result that every 
individual of the tribe must become exceedingly like to each other, not only in 
outer appearance, but also in organisation generally, and, as the descendants of 
the strongest, being exceedingly strong themselves. 
Some varieties may also be preserved by quite accidental circumstances.. 
Leaf-eating insects of greenish tints, for instance, have a better chance of 
avoiding discovery by their enemies than those whose bright colours serve to 
attract their destroyers. ‘The same applies to birds and animals having colours. 
similar to the places where they live—partridges, quails, larks, hares, are earth- 
coloured. The desire for reproducing their species is also as powerful an agent 
for development as the strugele for existence. Males struggle for the posses-. 
sion of females, either by combat, as in the case of the monkey just mentioned, 
and the systematic wars carried on by stages during the season, or by means of 
displaying before the females some advantages in form, in colour, in plumage.. 
Males and females of indifferent qualities are in this way excluded from having- 
offspring. It is evident also that such individuals chiefly become progenitors of 
offspring who, apart from having more perfect constitutions than others, 
exerted themselves in a higher degree to obtain sexual intercourse—7.e., whose: 
sexual organs are more perfectly developed. 
Thousands and thousands of years have elapsed, during which plants and 
animals have existed and developed under the influence of the conditions we: 
have just mentioned, and we are justified in supposing that the striking 
similarity of individuals of the same wild race, and the strong tendency of 
producing the almost identical characteristics of form, colour, temper, inclinations,. 
and habits, is owing to those causes which we have mentioned. There is no 
evidence that they were produced by any other causes. The strongest, 
healthiest, most beautiful animals, both male and female, survived in that 
constant struggle for existence and sexual intercourse, the inferior ones perished.. 
If we consider now that a comparatively short time would have been suflicient 
to overcrowd the earth and the ocean with living things if that struggle had not 
existed, we cannot help feeling that the wild races now extant owe their’. 
existence to the closest possible and successful competition for life and sexual 
—— EE 
