But with this enormous multiplication of the bacilli, other events followed. Carried north and east by winds, these huge quantities of the germs found their way into the headwaters of the Amazon and its tributaries, and were thus carried eastward into the very heart of the tropical forests, where they continued to breed with almost inconceivable rapidity. Soon the whole of the vegetation in this region was in a decline; and the Amazon valley degenerated into a swamp choked with dead and dying plants. Humanity was driven out long before the end came. Animal life could not persist in the midst of this noisome wilderness. The same phenomena appeared, though in a different form, over the southern part of South America. Here also the great rivers formed the main distributing agencies for the bacilli; and the whole cattle-raising district was devastated. The stock was slaughtered on a huge scale as soon as it became clear that vegetation had perished; but owing to mismanagement and transport difficulties the preservatives necessary to make the best of the meat thus obtained were not procurable in sufficient quantities. Nevertheless, by converting as much as possible into biltong, more than sufficient was preserved to keep a very large part of the population alive during the Famine; and in later days, by trading their surplus dried meat for cereals and nitrogenous compounds, they succeeded in rescuing a greater proportion of lives than might have been anticipated. To complete this survey of the world at that period, the effect of _B. diazotans_ upon North America still remains to be told. I have already given some information with regard to the spread of the Blight across the Middle West; but I must mention that it was in this part of the world especially that these curious isolated immune areas were observed, wherein the bacillus seemed to make no headway. Thousands of acres in all were found to be untouched by the denitrifying organisms. At the time of the Famine the civilisation of North America was in a curious condition, mainly owing to the influx of a foreign element which had taken place to a greater and greater extent after the War. The immigrants had come in such numbers that assimilation of them was impossible, and in this way the stability of the central Government was weakened. To a great extent the Southern States had fallen into the hands of the negroes, but similar segregations were to be found in other parts of the country. Germans accumulated in one State, Italians in another, East Europeans and Slavs in yet other areas. Thus Congress became subject to the group system of government, with all the weaknesses which such a system brings in its train.