The obvious test was employed of trying to drown the supposed odour of the female by filling the room she was in with powerful aromas, like naphthaline, paraffin, the alkaline sulphides, and the like. But in spite of the presence of these stenches, in our experience overwhelming to fainter exhalations, the males still continued to arrive in droves. This result led Fabre to doubt whether it could really have been an odour that attracted them. But surely this negative conclusion ignores the possibility of the moths being anosmic to these gross scents while highly specialised for one particular olfactory stimulus to which, as a matter of fact, we ourselves are wholly insensitive. Apart from this particular problem, however, to which we return below, biologists agree that insects undoubtedly possess an olfactory sense capable of appreciating the same kind of odours as ours does. Lubbock, for example, demonstrated that ants give signs of perceiving the presence of musk and other perfumes. There is no doubt, indeed, that the olfactory sense plays a great, it may be a preponderating part in their life-activity. The olfactory organ of insects is situated at the bottom of little crypts in the antennæ and in the palpi of the mouth apparatus, more particularly in the antennæ. And those insects, like bees, wasps, butterflies and moths, that frequent flowers, are attracted to them by their perfumes as well as by their colours. It has been found, for example, that covering up flowers from view does not put a stop to the visits of insects. Some naturalists go so far, indeed, as to say that odour is their principal guide. At all events, the sarcophagic and stercophagic insects are attracted to their food chiefly, if not entirely, by odour. Fabre has recorded how such insects are lured to their death by certain insectivorous plants which exhale a smell like that of putrid beef. In this connection I may interpolate here an experience which shows that this class of insect may be attracted solely by odour. Incidentally, it also manifests how the olfactory sense of insects can be utilised in the matter of hygiene.