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INSTINCTS AND HABITS.

up, for instance, to the third stage, and were put into one finished up to the sixth stage, so that much of its work was already done for it, far from feeling the benefit of this, it was much embarrassed, and, in order to complete its hammock, seemed forced to start from the third stage, where it had left off, and thus tried to complete the already finished work.'

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Another very interesting series of observations which we owe to M. Fabre has reference to the question of sex, and it would really seem that the mother can regulate the sex of the egg at will. In many of our wild bees, the females are much larger than the males. The male lives a life of pleasure, idle but short. "Quinze jours de bombance dans un magasin à miel, un an de sommeil sous terre, une minute d'amour au soleil, puis la mort."

But the female "C'est la mère, la mère seule qui, péniblement, creuse sous terre des galeries et des cellules, pétrit le stuc pour enduire les loges, maçonne la demeure de ciment et de graviers, taraude le bois et subdivise le canal en étages, découpe des rondelles de feuilles qui seront assemblées en pots à miel, malaxe la résine cueillie en larmes sur les blessures des pins pour édifier des voûtes dans la rampe vide d'un escargot, chasse la proie, la paralyse et la traîne au logis, cueille la poussière pollinique, élabore le miel dans son jabot, emmagasine et mixtionne la pâtée. Ce rude labeur, si impérieux, si actif, dans lequel se dépense toute la vie de l'insecte, exige, c'est évident, une puissance corporelle bien inutile au mâle, l'amoureux désœuvré."

In the hive bee the drone cells differ materially in shape from those of the queens and workers.

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INFLEXIBILITY OF INSTINCT.

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In the solitary wasps, where the females are much larger than the males, the mother builds a larger cell and provides more food for the former than for the latter.

The Chalicodoma (one of the mason bees) often lays her eggs in old cells of the previous year. These are of two sizes-large ones, originally built for the females, and small ones for the males. Now, in utilizing old cells, the bee always places male eggs in male cells and female eggs in female cells. If, however, a female cell be cut down so as to reduce the size, then indeed the bee deposits in it a male egg.

The bees belonging to the genus Osmia* arrange their cells in a row in a hollow stick, or some other similar situation, and it has long been known that in these and similar cases the cells first provisioned, and which are therefore furthest from the entrance, always contain females, while the outer cells always contain males.

There is an obvious advantage in this, because the males come out a fortnight or more before the females, and it is, of course, convenient that those which have to come out first should be in the cells nearest the door. The bee does not, however, lay all the female eggs first, and then all the male eggs. By no means. She produces altogether from fifteen to thirty eggs, but seldom arranges them in one row; generally they are in several series, and in every one the same sequence occurs-females further from, and males nearest to, the

door.

For instance, one of M. Fabre's marked bees—one, moreover, of exceptional fertility-occupied some glass

* Osmia tridentata constitutes an exception to the general rule in this respect, as in some others.

260 DIFFERENT HABITS OF MALES AND FEMALES.

tubes, which he arranged conveniently for her. From the 1st to the 10th of May she constructed, in one tube, eight cells-first seven female, and then one male. From the 10th to the 17th, in a second tube, she built first three female and then three male cells; from the 17th to the 25th, in a third, three female and then two male; on the 26th, in a fourth, one female; and, finally, from the 26th to the 30th, in a fifth, two female and three male: altogether twenty-five, seventeen female and eight male cells.

The advantage of this is clear, but the manner in which it is secured is not so obvious. It might be suggested that the quantity of food was not regulated by the sex of the young one, but that the sex depended on the quantity of food. This would be very improbable, and M. Fabre attempted to disprove it by some very ingenious experiments. He found that if he took some of the food from a female cell, the bee or wasp produced was still a female, though a starveling; while if he added food to a male cell, the larva still produced a male, though a very large and fine one.

M. Fabre then made some of his most ingenious experiments. He brought into his room a large number of cocoons of Osmia. When the perfect insects were about to emerge, he arranged for them a number of glass tubes, of which the Osmias gladly availed themselves, and in which they proceeded to construct their cells. The usual arrangement, as already mentioned, is that the males are placed nearest to, and the female furthest from, the door. But M. Fabre so arranged the tubes that each was in two parts, an outer wider portion having a diameter of eight to twelve millimetres, which is sufficient for a female cell; and an

ARRANGEMENT OF MALE AND FEMALE CELLS. 261

inner narrower portion with a diameter of five to five and a half millimetres, which is too small for a female, but just large enough for a male. This arrangement placed the Osmias in a difficulty. They could not follow their natural instinct and construct at the end of the tube cells large enough for females.

What happened? Some of the Osmias shut off the narrow ends, and used only the outer wider portion. Others, reluctant, as it were, to throw away a chance, built also in the narrow part of the tube, and under these circumstances, contrary to the otherwise invariable rule, the inner and first constructed cells contained males.

M. Fabre concludes then, and it seems to me has given very strong reasons for thinking so, that these privileged insects not only know the sex of the insect which will emerge from the egg they are about to lay, but that at their own will they can actually control it! Certainly a most curious and interesting result!

He concludes his charming work as follows:-"Mes chèrs insectes, dont l'étude m'a soutenu et continue à me soutenir au milieu de mes plus rudes épreuves, il faut ici, pour aujourd'hui, se dire adieu. Autour de moi les rangs s'eclaircissent et les longs espoirs ont fui. Pourrai-je encore parler de vous?" and every lover of nature will, I am sure, echo the wish.

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CHAPTER XIII.

ON THE SUPPOSED SENSE OF DIRECTION.

ONE of the most interesting questions connected with the instincts and powers of animals has reference to the manner in which they find their way back, after having been carried to a distance from, home. This has by some been attributed to the possession of a special 66 sense of direction."

Mr. Darwin suggested that it would be interesting to try the effect of putting animals "in a circular box with an axle, which could be made to revolve very rapidly, first in one direction and then in another, so as to destroy for a time all sense of direction in the insects. I have sometimes," he said, "imagined that animals may feel in which direction they were at the first start carried." In fact, in parts of France it is considered that if a cat is carried from one house to another in a bag, and the bag is whirled round and round, the cat loses her direction and cannot return to her old home.

On this subject M. Fabre has made some interesting and amusing experiments. He took ten bees belonging to the genus Chalicodoma, marked them on the back with a spot of white, and put them in a bag. He then carried them half a kilometre in one direction, stopping at a point where an old cross stands by the

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