The dragonfly possesses the unique faculty among winged creatures, birds or insects, of flying backwards and forwards and sideways without turning its body. There are very few insects that the swallow, with its marvelous speed and dexterity, cannot catch, but the dragonfly is one them. The dragonfly without any apparent trouble, will keep a few feet ahead of a swallow for half an hour at a stretch, and no matter how swiftly the swallow flies, the dragonfly is never just there when it makes its swoop. This is because the swallow has to turn its body, while the dragonfly only reverses its wings. * * * * * The investigations of Professor Weismann have done more to solve the problem, "How death came into the world" than those of any other living man. It is generally assumed that death is associated with all forms of life, but this is not really the case. The lower forms of life, for example, may be said to have a perpetual existence, and not to be subject to death; for in unicellular reproduction life is practically endless. In the case of higher forms of life death is universal, and for a very natural reason. The aim of nature is the perpetuation of the species, not of the individual, and when creatures have, as in the case of certain insects, reproduced themselves once for all, they have no further need of existence. Creatures that nurse their young, like mammals, and produce them slowly, have need of longer life, or the species would speedily be exterminated; but there is no reason why the individual, having performed its duty in relation to the species, should continue to exist, since its existence then becomes a superfluity. Between multicellular and unicellular existence there is, therefore, the marked difference that, whereas the former dies when it has reproduced itself and so perpetuated its species, the latter goes on perpetually reproducing itself--one cell growing out of another without cessation. To Weismann we owe the knowledge of how it is that death intervenes when multicellular existence develops from unicellular. The change is effected by the differentiation of the individual--or somatic--and the reproductive cells. The former have lost the power of multiplication and reproduction, and consequently died, while the latter have preserved it. * * * * *