130 GENERAL PHYSIOLOGY 



animalcules, or Rotatoria, whose bodies, extended like a telescope, 

 have at their anterior end a locomotor organ provided with stout 

 cilia, which on account of the apparently wheel-like motion of the 

 cilia has been termed the wheel-organ. Besides the Rotatoria 

 there are found chiefly the so-called bear-animalcules, or Tardi- 

 grada, clumsy mite-like animals provided with four pairs of short 

 stumps of feet, bearing claws ; like the Rotatoria they are provided 

 with a nervous system, digestive apparatus, etc. (Fig. 41 a). So 

 long as this latter peculiar animal is in water, it performs all 

 its vital phenomena like other animals. But if it be isolated 

 and allowed to dry slowly upon a slide, it is seen that the 

 more the water evaporates, the slower become its movements, 

 until finally they cease entirely when the drop is dried up. Then 

 the body gradually shrinks, the skin becomes wrinkled and folded, 

 the form becomes gradually indistinguishable, and some time 

 after the animal has become dried up it can scarcely be dis- 

 tinguished from a grain of sand (Fig. 41 fr). In this dried con- 

 dition it can remain for many years without undergoing the 

 slightest change. If it be moistened again with water, the 

 return of life to the desiccated body after its sleep can be 

 followed with the microscope. The awakening of the tardi- 

 grade, or the anabiosis, as Preyer ('80) has termed the process, 

 takes place somewhat as follows: The body swells up and becomes 

 extended, the folds and wrinkles slowly disappear, the extremities 

 project, and the animal soon assumes its normal shape. At first 

 it remains quiet ; then, after a time, varying, according to the 

 duration of the drying, from a quarter of an hour to several hours, 

 movements, at first slow and feeble, begin and gradually become 

 stronger and more frequent, until after some time the animal, 

 unaided, creeps away to resume life at the point where it was 

 interrupted. 



These highly remarkable phenomena of anabiosis are not limited 

 to the Rotatoria and the Tardigrada. They have been noticed 

 likewise in various other organisms in the course of investigations 

 which in great number followed Leeuwenhoek's discovery. They 

 have been observed in the so-called paste-eels, or AnguUlulidce, 

 the small eel-like worms that live in diseased wheat-grains, in 

 Infusoria and Amoeba, and in Bacteria, 



In the same group of facts belongs also the long-known capacity 

 of plant-seeds to remain dry for many years unchanged without 

 losing their power of sprouting ; indeed, it has even been believed 

 that this power can continue for an unlimited time. The state- 

 ments are well known that wheat-grains found in the graves of 

 Egyptian mummies after a rest of many thousand years have 

 sprouted and bloomed. It has been settled, however, that these 

 reports rest upon a delusion, for Mariette, the well-known Egypto- 

 logist, has shown that with genuine mummy wheat these experi- 

 ments always fail, since all wheat-grains taken from the graves 



