correspondence. 241 



Desiccation op Rotifers. 



To the Editor of the ' Monthly Microscopical Journal.' 



April 7, 1873. 



Sir, — I have not been able to find the latest papers on the desicca- 

 tion of rotifers, to which I referred on 2nd April, when Mr. Davis 

 brought the subject before the Koyal Microscopical Society, and 

 which, I thought, had appeared within three or four years in ' Coniptes 

 Eendus.' 



The following extracts and references will, however, show that 

 the question was investigated and settled at an earlier date. 



F. A. Pouchet speaks thus in his 'Universe' (English transla- 

 tion, p. 52) : " This pretended revival is only the same phenomenon 

 as is exhibited by the snail which, when placed in a dry spot, buries 

 itself in its shell till a little moisture is imparted to it." Mr. Wenham 

 mentioned an interesting instance of this revival on the 2nd, which 

 will be found in your report. Pouchet continues, " It has been main- 

 tained that the contracted rotifer is absolutely dry, and consequently 

 dead, but this is not the case. When it is thoroughly dried it never 

 recovers. The prestige of these resurrections was doomed to vanish 

 in the laboratory of the Museum of Natural History at Rouen. Many 

 of my pupils joined with me in bringing back science to rational 

 views. Professor Pennetier, by his memorable labours, proved that 

 the anguilluke do not revive. M. Tinel did the same with the tardi- 

 grades ; I myself as far as regards the rotifers." 



In a foot-note M. Pouchet says, " Dr. Pennetier, in a series of valu- 

 able observations, has proved the complete absurdity of resurrections 

 in general. In his special experiments upon anguillulte, he noticed 

 that, so far from supporting complete desiccation, they succumbed at a 

 heat of 70° C. (158° F.). See 'Memoires sur les Rotiferes,' Ann. des 

 Sciences, 1859 ; ' Memoires sur les Tardigrades,' Ann. des Sciences, 1859 ; 

 ' Memoires sur la Revivification des Rotiferes,' Soc. de Biologie, 1859; 

 ' Memoires sur les Anguillules des Toits,' Soc. de Biologie, 1859 ; 

 1 Recherches sur les Anguillules,' Ann. des Sciences, 1860 ; ' De la 

 Revivescence des Animaux dits . Resuscitants,' Actes du Museum 

 d'Histoire Naturelle de Rouen, 1862. He gives references to M. 

 Tinel's experiments, Soc. de Biologie and Union Medicale 1869, and to 

 his own experiments, showing that desiccation carried to 90° C. infal- 

 libly kills rotifers. — Comptes Bendus, 1859, &c. 



In ' L'Origine de la Vie,' par le Docteur George Pennetier, Paris, 

 1868, in the chapter entitled " Les Pretendus Incombustibles," the 

 author investigates various questions of alleged resurrections of orga- 

 nized beings after exposure to heat sufficient, or more than enough to 

 dry them, and gives various details of opinions, and experiments with 

 rotifers. He quotes Pouchet to the effect that " rotifers and tardi- 

 grades may be subjected to a cold of 17° C, then exposed suddenly to 

 95° C. without losing their property of revival." At p. 157 he figures 

 the apparatus he used to ensure the thorough drying of rotifers — a 

 process which killed them all. He exposed them to a current of dried 

 air at temperatures gradually brought up to 100° C. (212° F.). The 



