_Wasps._--These usually construct their nests of wood-dust, which they scrape off the weather-worn surfaces of boards, palings, &c., and work into a kind of paper with their saliva. If they happen to find any real paper, they perceive that it so much resembles the product of their own manufacture that they utilise it forthwith. The wasps do not require any special cells or chambers for the storage of honey, as they do not lay up any supply for the winter. The cells which they construct are therefore used exclusively for the rearing of larvæ. In form these cells are sometimes cylindrical or globular, but more usually hexagonal, like those of the hive-bee. Although the mode of building is different from that employed by the bees, there can be little doubt that if it were as carefully investigated Mr. Darwin's theory of transition from the cylindrical to the hexagonal form would be found to apply here also, seeing that both forms so frequently occur in the same nest. _The Mason-Wasp._--The habits of this insect are described by Mr. Bates. It constructs its nest of clay. Each pellet that the insect brings it lays on the top of its nest-wall, and then spreads it out with its jaws, and treads it smooth with its feet. The nest, which is suspended on the branch of a tree, is then stocked with spiders and insects paralysed by stinging. The victims, not being wholly deprived of life, keep fresh until required as food of the developing larvæ. _The Butcher-Wasps._--These also paralyse their prey in a similar manner, and for a similar purpose. Fabre removed from a so-called sphex-wasp a killed grasshopper, which it was conveying to its nest and had momentarily laid down at the mouth of the burrow--as these insects always do on returning with prey, in order to see that nothing has intruded into the burrow during their absence. Fabre carried the dead or paralysed grasshopper to a considerable distance from the hole. On coming out the insect searched about until it found its prey. It then again carried it to the mouth of its burrow, and again laid it down while it once more went in to see that all was right at home. Again Fabre removed the grasshopper, and so on for forty times in succession--the sphex never omitting to go through its fixed routine of examining the interior of its burrow every time that it brought the prey to its mouth. Mr. Mivart, in his 'Lessons from Nature,' points to the instinct of this animal in the stinging of the ganglion of its prey as one that cannot be explained on Mr. Darwin's theory concerning the origin of instincts. In my next work, which will have to deal with this theory, I shall consider Mr. Mivart's difficulty, and also the difficulty first pointed out by Mr. Darwin himself as to why neuter insects, separated as they appear to be from the possibility of communicating by heredity any instinctive acquirements of the individual to the species, should present any instincts at all. _General Intelligence._