2G M. Doyere on the Hevivi/icafmi of Animals of the 



deny, in the most positive manner, what has been termedthe 

 Hcvmfication of Fotifera. 



Latterly, it is true M. Schultz has successfully repeated 

 some of Spallanzani's experiments, and has furnished many 

 naturalists with the opportunity of making similar researches ; 

 but still more lately, M. Ehrenberg has added the weight of 

 his great authority to the opposite opinion ; and having for- 

 mally rejected the opinion of Spallanzani, has attempted to 

 explain the way in which an error of the kind could find its 

 way into science. 



This interesting and much debated question, then, could not 

 be considered as definitely settled, and appeared to demand 

 further investigation. It was necessary to examine carefully 

 all the circumstances attending the phenomena described by 

 Leuwenhoeck, Needham, and Spallanzani, to submit to the 

 proof of experiment, the objections and hypotheses presented 

 by others, antagonists of these celebrated observers, and to ac- 

 quire new facts by which one or other of the contradictory 

 opinions of naturalists might be supported or refuted. This 

 difl&cult task has been undertaken by M. Doyere. 



The FoUfera and the Tardigrada are found, as is well known, 

 in the moss growing u^Jon roofs, or in the sand found in the 

 gutters of the roof, and are seen in the living state when these 

 matters, after having been for a long time dry, are wetted with 

 water. The fact of ^the appearance of these animalculas in a 

 living state in dust which had been dry during months, or even 

 whole years, can no longer be disputed, and it is equally well 

 demonstrated that, with these minute beings as with animals 

 of a higher class, evaporation of their fluids, carried to a cer- 

 tain extent, induces the abolition of every sign of vital mo- 

 tion. The pai'tizans of Spallanzani's opinion regard the re- 

 appearance of these living beings as a sort of resurrection ; 

 and the advocates of the contrary opinion think that the phe- 

 nomena may be explained in a simpler manner ; the opinion 

 is, that the Rotifera, &c. are of an amphibious nature, and ca- 

 pable of living in dry air as well as in water or sand, where 

 the moss with which they are surrounded would preserve them 

 from too complete desiccation, so that in fact, in the above 

 cited instances, the active state of the animalculae would never 



