52 THE UNIVERSE. 



and formidable transition from cold to heat, these minute 

 animals passed rapidly through a change of 216 Fahr. 

 without being in the least inconvenienced by it. 



An ox could not bear with impunity what imperceptible 

 animalcules endure. 1 



CHAPTER VII. 



THE SPONGE AND THE FLINT. 



THESE two names seem to form an antithesis, but not so 

 absolutely in natural history as might be supposed, for 

 sometimes one of these bodies is derived from the other. 

 But what connection can there be between our soft and 

 flexible sponges and the hard flint from which the steel 

 draws sparks ? Let us see. 



From Aristotle down to our days men have never known 

 to what kingdom the sponges should be relegated. At the 

 present time some naturalists consider them as vegetables ; 

 others, on the contrary, rank them among the animals. 



1 M. Broca remarks as follows on one of my experiments on this extraordinary 

 vital tenacity : " Of all the tests to which these revivable animals have been sub- 

 jected, the above is certainly the most astounding. Before this beautiful experi- 

 ment was performed by M. Bouchet, we had only a very indistinct idea as to the 

 power of resistance possessed by the tardigrades and rotifers, and it is almost 

 incredible that, when so suddenly heated, in an instantaneous rise, indeed, of al- 

 most 180 Fahr., the sudden dilatation of the tissues did not produce rupture of 

 them. But we cannot resist the evidence, and we are bound to say that M. Bou- 

 chet has discovered one of the most extraordinary properties of the rotifers and 

 tardigrades." Broca, Etudes sur les Animaux Ressuscitants. Paris, 1860, p. 59. 

 Since that date I have succeeded in suddenly raising the temperature of the 

 pseudo-resuscitating animalcules 216 Fahr. 



