III. Such are the data by which we are enabled to judge of the attempts at acclimatisation made by man himself. I cannot too often repeat the fact that, in common with organised and living beings, we are subject to all the general laws which govern life and organisation in animals and plants. Our intelligence is unquestionably of assistance to us in our struggles with nature, but, unfortunately, the power which we derive from her is limited, and in no case are we placed at greater disadvantage than in the increasing struggle demanded by a considerable change in conditions of life. The most ingenious efforts are then unable to free man from vicissitudes more or less analogous to those suffered by the wheat of Sierra Leone, the fowls at Cuzco, and the geese at Bogota. We must, then, almost always be prepared for sacrifices, the extent and gravity of which will be proportionate to the differences, as regards conditions of existence, between the two countries, and we must almost always expect to lose a certain number of individuals and generations. Everything depends upon judging facts fairly, not exaggerating their importance, and seeing how far they justify a hope of success in spite of appearances. If the losses are merely equal to those I have just mentioned, or, better still, if they are fewer in number, we may prophesy a favourable result; and, if the victory is worth the price, we must leave the rest to perseverance and time. IV. Events in Algeria confirm these observations. After the conquest it was everywhere, as also in France, a question whether it would be possible to colonise the country taken from the Turks and Arabs. Dr. Knox declared most emphatically that such a colonisation was impossible, and that the French would never be able to increase or even live in Africa. It must be confessed that this opinion found many and strong supporters. After the first few years of occupation the generals, as well as the doctors, were almost all of the same opinion. M. Boudin supported, with distressing statistics, the views of his colleagues, Marshal Bugeaud and Generals Duvivier and Cavaignac.