PHYSIOLOGICAL 273 



many of the seeds in the seedsman's shop, and a desiccated thread- 

 worm may be so dry that it breaks when we touch it with a needle. 

 Yet, when water is suppUed, it becomes agile once more. It seems, 

 then, that the groups of large molecules — proteins in particular — 

 may entirely cease their reactions with one another and with the 

 outside world, without this necessarily precluding the reassumption 

 of active relations at a subsequent date. The fatal change begins 

 when the protein molecules begin to disintegrate. Even here, how- 

 ever, there may be no more than local death ; for fatal disintegration 

 may occur in a part without any surrender of the whole citadel of 

 life. In many animals, as in most plants, the dying away of parts is 

 normal. 



Let us summon the "seven sleepers" before us. First, from the 

 gutters of houses, come the sluggish microscopic "bear-animalcules", 

 with four pairs of clawed legs. Some of them, seen sideways, are 

 quaintly like minute rhinoceroses. When they are dried up, they 

 become like much- weathered grains of sand; and they may remain 

 for years without any discernible vitality. But when they are once 

 more supplied with water, they swell up again and crawl away, as 

 plump as little sucking-pigs. 



Second, from amid moist bog-moss come the beautiful "Wheel 

 animalcules" or rotifers, which often show an astounding capacity 

 for "suspended animation". Sometimes the entire animal survives 

 the prolonged drought; sometimes the body succumbs, but the 

 eggs live on. Two hundred years ago the keen-eyed Leeuwenhoek 

 was delighted to observe that the "wheels" began to go round again 

 after they had entirely stopped during a prolonged drought. 



Third, from damp earth and decaying organic matter, there comes 

 a large contingent of paste-eels, vinegar-eels, ear-cockle worms, and 

 other Nematodes, some of which can survive desiccation or drying-up 

 for as many as twenty years. In this and in some other cases the 

 process of revivification takes a longer or shorter time according to 

 the duration of the dried-up quiescence when "life" appeared to be 

 absent altogether. 



The fourth set of sleepers are among the jointed-footed animals, 

 or arthropods, including notably the thousands of insects that pass 

 the winter in a state of suspended animation as larvae, or as pupae, 

 or as adults. They become benumbed, we say, but we do not satis- 

 factorily understand what happens. Their muscles go out of gear, 

 and not only is there an entire stoppage of movement, but a loss of 

 irritability to all sorts of stimuli. With this arthropod contingent 

 should be associated the numerous minute crustaceans, which may 

 become as dry as dust and remain so for years without a loss of 

 vitality. When an egg, an embryo, or a seed remains in a state of 

 latent life in this way, the marvel is big enough, but it is enhanced 

 when we have to do with an intricate adult creature possessed of a 



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