254 EXTRACTS AND ABSTRACTS FROM FOREIGN JOURNALS. 



It is known that animals perish when their temperature is raised 

 above a certain limit, inferior, however, to that at which the white of 

 egg coagulates, and which, in the majority of cases, does not exceed 

 50 cent. (122 F.) Animalculae capable of resurrection are not 

 excepted from this law ; M. Doyere is satisfied that the Rotifera and 

 Tardigrada perish when the water in which they swim is heated to 45 

 cent. (105 F.) and that they cannot then be recalled to life by any 

 means. But he has found that this is not the case when the animalculse 

 have been previously dried. If, instead of experimenting upon Tardi- 

 grada in full life, it is done upon individuals 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 faculty 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 Tardigrada, after having been properly 

 dried, was placed in a stove, and around the bulb of a thermometer, the 

 stem of which extended out of the apparatus ; heat was gradually 

 applied, until the thermometer thus placed in the centre of the moss, 

 indicated a temperature of 120 cent. (248 F.) This considerable heat 

 was maintained for several minutes, nevertheless, some of the animal- 

 culse 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 experiments, M. Doyere submitted some dried 

 animalculse to a heat of more than 140 cent. (284 F.), and still -wit- 

 nessed some of them revive after immersion in water. These facts are 

 in themselves of considerable importance towards the solution of the 

 question at issue, and the result without doubt depends npon the cir- 

 cumstance first pointed out by M. Chevreul, that albumen, deprived of 

 its water by previous drying, can be submitted to a much higher tem- 

 perature 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 c. (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 consi- 

 dered as actually alive, and their 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 and of heat, but 

 which, in the absence of one of these excitants, manifests no sign of 

 activity or life, and can be preserved thus for ages, although the dura- 

 tion of its real life may not exceed perhaps a few weeks. 



M. Doyere has also given a detailed and excellent account of the 

 anatomy of these animalculae, including, especially, the nervous and 

 muscular systems ; and his work is illustrated with beautiful and exact 

 figures. 



