That ants track one another by scent was long ago mentioned by Huber, and also that they depend on this sense for their power of finding supplies which have been previously found by other ants. Huber proved their power of tracking a path previously pursued by their friends, by drawing his finger across the trail, so obliterating the scent at that point, and observing that when the ants arrived at that point they became confused and ran about in various directions till they again came upon the trail on the other side of the interrupted space, when they proceeded on their way as before. The more numerous and systematic experiments of Sir John Lubbock have fully corroborated Huber's observations, so far as these points are concerned. Thus, to give only one or two of these experiments; in the accompanying woodcut (Fig. 1) A is the nest, B a board, _n_ _f_ _g_ slips of paper, _h_ and _m_ similar slides of glass, on one of which, _h_, there was placed pupæ, while the other, _m_, was left empty. Sir John Lubbock watched two particular (marked) ants proceeding from A to _h_ and back again, carrying the pupæ on _h_ to the nest A. Whenever an ant came out of A upon B he transposed the slips _f_ and _g_. Therefore at the angle below _n_ there was a choice presented to the ant of taking the unscented pathway leading to the full glass _h_, or the scented pathway leading to the empty glass _m_. The two marked ants, knowing their way, always took the right turn at the angle; but the stranger ants, being guided only by scent, for the most part took the wrong turn at the angle, so going to the empty glass _m_. For out of 150 stranger ants only 21 went to _h_, while the remaining 129 went to _m_. Still the fact that all the stranger ants did not follow the erroneous scent-trail to _m_, may be taken to indicate that they are also assisted in finding treasure by the sense of sight, though in a lesser degree. Therefore Sir John Lubbock concludes that in finding treasure 'they are guided in some cases by sight, while in others they track one another by scent.' [Illustration: Fig. 1.]