THE CONDITIONS OF LIFE IN ANIMATED BEINGS. 431 



All those industrious insects that are commonly 

 called solitary bees and reason-bees are equally 

 exposed to receiving the visits of hymenoptera 

 of the same family that have no power to work ; 

 but these strangers do not wear the livery of the 

 species whose nests they invade ; nor do they 

 need it, as they proceed only by skill and craft. 

 The solitary bee builds, by itself, the cradle of 

 its offspring, and stores in each cell a supply of 

 food just sufficient for the grub that is to be its 

 tenant. In search of its provision it is obliged to 

 be often absent ; the bee that does not work, and 

 has no other care than to contrive the deposit of 

 an egg in the cell where its grub will eat the 

 stock laid up for that of the laboring species, 

 keeps in the neighborhood of the nest at which 

 honey and pollen are arriving ; it studies the 

 position, takes advantage of the owner's absence 

 to penetrate into the retreat, lays an egg in it, 

 and then escapes by stealth, like the robber who 

 is well aware of the risk he would run should he 

 chance to be met. 



When we direct our attention to the cir- 

 cumstances of the life of animated creatures, we 

 are greatly struck by seeing on the one hand for- 

 tunately-endowed beings, whose conditions of .ex- 

 istence seem full of charm, and on the other hand 

 beings less favored, and even some that are in a 

 manner disinherited, and that find life possible 

 only by the assistance of species which have the 

 gift of strength or of skill. Hence result certain 

 really extraordinary associations of animals ; some- 

 times the luckless one expects his subsistence 

 from the good-will of the better endowed ; oftener 

 the weak accompanies the strong either to be 

 carried about with it, or to profit by the leavings 

 that the latter drops. M. van Beneden, the dis- 

 tinguished professor of the University of Louvain, 

 calls these creatures that are thus attached to the 

 fortunes of others commensals. 



In some ant-hills little bright coleoptcra live 

 that are called clavigcri ; their heads are crowned 

 with thick antennas, and on the sides of their 

 bodies grow tufts of hairs. These creatures are in- 

 deed disinherited ; completely blind, with mouths 

 having their articulated parts very small, and 

 scarcely movable, they cannot eat of there- 

 selves, and the aid of the ants is indispensable to 

 them. Between these insects there exists a con- 

 nection of the most extraordinary sort, which has 

 been very closely observed by an able naturalist, 

 M. Lespes. The clavigeri shed a sweet fluid, 

 which clings to their hairy tufts ; the ants, greedy 

 for anything that is sugary, swallow this fluid, 

 and the clavigeri become favorite guests for them. 



In return for their good offices, they feed them 

 by mouthfuls. When an ant-hill is disturbed, 

 every one knows with what zeal, activity, and 

 anxiety the ants carry off their grubs and nymphas 

 to put them out of the reach of danger. They 

 act in the same way with regard to the clavigeri 

 when they suppose them to be threatened. In 

 spite of all this, a dependent condition is the fate 

 of the latter in the community, in which each one 

 finds its part ; it is slavery made inevitable by 

 defects in organization. For the philosopher, 

 there is, perhaps, one thing even more interesting 

 than this state of slavery in the relations between 

 ants and clavigeri. The repeated experiments of 

 Lespes prove that ants need some training to ap- 

 preciate the benefits they may gain from these 

 little bright coleoptera. All ant-hills of the same 

 species do not own clavigeri. If one takes a 

 fancy to put a few of these poor blind things into 

 a nest where there are none of them, the ants 

 have no suspicion of the happiness intended to 

 be provided for them. With their instinct of 

 seeking to account for everything that takes place 

 in their dwelling, they examine the intruders, and, 

 failing to discover the possibility of getting any 

 good out of them, they pull them to pieces. 



In some companionships of individuals of dif- 

 ferent species, a sort of equality rules : that of 

 the mussel and the little crab known by the name 

 of the pinnothera gives an instance of this. The 

 pinnothera, which has been very unjustly charged 

 with possessing properties injurious to the ani- 

 mal economy, finds a shelter in the mussel. Cov- 

 ered by a shell of stony hardness, armed with 

 powerful claws, and gifted with excellent sight, it 

 falls suddenly on its prey, and quietly devours it, 

 the mussel receiving the remnants. It gives 

 food, and receives lodging in return. Most fre- 

 quently the association is of advantage only to 

 the weaker individual, which, moreover, is the 

 only one of the two that seeks it. Some quite 

 small fish take up their abode in the mouth of 

 a large species of silurus on the Brazilian coast, 

 which is skillful in fishing with the help of its 

 beard-like appendages, and there seize what they 

 require as it goes by. A slender-shaped fish of 

 the Mediterranean, the fierasfcr, rather ill adapted 

 for pursuing its prey, makes its way into the 

 stomach of the holothuria, where it feeds at its 

 ease. The holothuria are zoophytes covered by 

 a very leathery integument, and having the mouth 

 encircled by branchy tentacles. The Chinese eat 

 them, particularly the kind that is known as the 

 edible trepang. Many animals with very imper- 

 fect means of locomotion, especially some crus- 



