There are many lesser peculiarities connected with the soils of North America that have had considerable influence upon the history of the people; the most essential fact is, however, that the climatic conditions of this continent are such that all the important European products, except the olive, will flourish over a wide part of its surface. So that the peoples who come to it from any part of Europe find a climate not essentially different from their own, where the plants and animals on which their civilization rested would flourish as well as in their own home.[5] We may note also that the climate of North America brought Europeans in contact with no new diseases. North of the Gulf of Mexico the maladies of man were not increased by the transportation from Europe. It is difficult to arrive at a satisfactory determination concerning the effect of American conditions upon the peoples who have come from Europe to live a life of many generations upon its soil. Much has been said in a desultory way upon this subject, but little that has any very clear scientific value. The problem is a very complicated one. In the first place it is very difficult, if not impossible, to separate the effects of climate from those brought about by a diversity of the social conditions, such as habits of labor, of food, etc. Moreover, the problem is further complicated by the fact that there has been a constant influx of folk into America from various parts of Europe, so that in most parts of the country there has been a constant admixture of the old blood and the new. After reviewing the sources of information, I am convinced that the following facts may be regarded as established: The American people are no smaller in size than are the peoples in Europe from which they are derived; they are at least as long-lived; their capacity to withstand fatigue, wounds, etc. is at least as great as that of any European people; the average of physical beauty is probably quite as good as it is among an equal population in the Old World; the fecundity of the people is not diminished. The compass of this essay will not permit me to enter into the details necessary to defend these propositions as they might be defended. I will, however, show certain facts which seem to support them. First, as regards the physical proportions of the American people. By far the largest collections of accurate measurements that have ever been made of men were made by the officers of the United States Sanitary Commission during the late Civil War. These statistics have been carefully tabulated by Dr. B. A. Gould, the distinguished astronomer. From the results reached by him, it is plain that the average dimensions of these troops were as good as those of any European army; while the men from those States where the population had been longest separated from the mother country were on the whole the best formed of all.[6]