T^/pes Tardigrada and Rotifera. 29 



animalculas have been previously dried. If, instead of ex- 

 perimenting upon Tardigrada in full life, it is done upon indi- 

 viduals which have lost all their humidity by the ordinary 

 means of desiccation, and which appear as dead, it is possible, 

 without depriving them of the facility of reviving, to raise their 

 temperature to a degree which would necessarily involve the 

 disorganization of all living tissue containing any water beyond 

 that chemically combined with its constituent principles. In 

 an experiment repeated in the presence of the commission of 

 the Academy, a certain quantity of moss, containing Tardi- 

 grada, after having been propei'ly dried, was placed in a stove, 

 and around the bulb of a thermometer, the stem of which ex- 

 tended out of the apparatus ; heat was gradually applied, until 

 the thermometer thus placed in the centre of the moss indi- 

 cated a temperature of 120^ cent. (248° F.) This considerable 

 heat was maintained for several minutes ; nevertheless, some 

 of the animalculae contained in the moss returned to life, and 

 appeared in their usual condition after they had been placed 

 for 24 hours in a suitable degree of moisture. In other ex- 

 periments, M. Doyere submitted some dried animalculae to a 

 heat of more than 140^ cent. (284° F.), and still witnessed 

 some of them revive after immersion in water. These facts 

 are in themselves of considerable importance towards the solu- 

 tion of the question at issue, and the result, without doubt, 

 depends upon the circumstance first pointed out by M. Chev- 

 reul, that albumen, deprived of its water by previous drying, 

 can be submitted to a much higher temperature, without, in 

 consequence, losing its solubility, than it could be if exposed to 

 the same temperature in the moist state ; and from the simple 

 fact that a Tardigrade, exposed to the action of a temperature 

 of 120° cent. (248° F.), can still be made to revive, it may be 

 concluded, with great probability, that the whole of the water 

 chemically free in its body had been dissipated, a degree of 

 desiccation which would preclude all idea of vital movement. 

 Thus the Tardigrada and Rotifera, when dry, and retaining 

 the property of living when moistened, cannot be considered 

 as actually alive ; and then- mode of existence can only be com- 

 pared to that of a seed, which is organized so as to live, and 

 which will live when exposed to the influence of air, of water, 



