ards which all his
reflective powers were being directed. Then, during a quiet time at
Sarawak, the accumulation of thought and observation found expression in
an essay entitled "The Law which has regulated the Introduction of
Species," which appeared in the _Annals and Magazine of Natural History_
in the following September (1855).

From November, 1854, the year of his arrival in the East, until January
or February, 1856, Sarawak was the centre from which Wallace made his
explorations inland, including some adventurous excursions on the Sadong
River. During the wet season--or spring--of 1855, while living in a
small house at the foot of the Santubong Mountains (with one Malay boy
who acted as cook and general companion), he tells us how he occupied
his time in looking over his books and pondering "over the problem which
was rarely absent from [his] thoughts." In addition to the knowledge he
had acquired from reading such books as those by Swainson and Humboldt,
also Lucien Bonaparte's "Conspectus," and several catalogues of insects
and reptiles in the British Museum "giving a mass of facts" as to the
distribution of animals over the whole world, and having by his own
efforts accumulated a vast store of information and facts direct from
nature while in South America and since coming out East, he arrived at
the conclusion that this "mass of facts" had never been properly
utilised as an indication of the way in which species had come into
existence. Having no fellow-traveller to whom he could confide these
conclusions, he was almost driven to put his thoughts and ideas on
paper--weighing each argument with studious care and open-eyed
consideration as to its bearing on the whole theory. As the "result
seemed to be of some importance," it was sent, as already mentioned, to
the _Annals and Magazine of Natural History_ as one of the leading
scientific journals in England.

In the light of future events it is not surprising that Huxley (many
years later), in referring to this "powerful essay," adds: "On reading
it afresh I have been astonished to recollect how small was the
impression it made."

As this earliest contribution by Wallace to the doctrine of Evolution[18]
is of peculiar historical value, and has not been so fully recognised as
it undoubtedly deserves, and is now almost inaccessible, it will be
useful to indicate in his own words the clear line of argument put forth
by him two years before his second essay with