difficulties which attend the preservation of the seed in the granaries in the south would be greatly increased in the wet climates of Northern Europe, and there, moreover, the greater cold would render the ants torpid almost throughout the winter, when food would not be required. But the question is plainly an open one. We may also ask why it is that only a very few out of the many species of ants which inhabit the shores of the Mediterranean should possess this habit of collecting seeds, and differ so widely in their manner of living, from their neighbours?
If we wish to put ourselves in the way to answer these queries, the first thing we should do would be to examine and compare the structure of the digestive organs and parts of the mouth in harvesters and non-*harvesters, with a view to seeing whether there may not be some capital difference here.
These observations demand some skill in dissection and preparation, and in regretting that it has not been in my power to make them, I can only hope that some one more skilled than I am may undertake the subject.
It seems probable, that in warmer latitudes there are many conditions which favour the rapid increase of ants, so that a given tract of country in Southern Europe, for example, must have on an average more colonies to support than a similar tract in the north, and that to meet this increase of population, it has therefore become necessary for these creatures to seek their subsistence from as many and as dissimilar sources as possible. The fierce conflicts over booty both between rival nests of the same and
