46 PHYSIOGNOMY OF PLANTS. 



stricter criticism, has been the subject of much animated 

 discussion. Baker affirmed that he had resuscitated, in 

 1771, paste-eels which Needham had given him in 1744! 

 Franz Bauer saw his Vibrio tritici, which had been dried up 

 for four years, move again on being moistened. An ex- 

 tremely careful and experienced observer, Doyere, in his 

 Memoire sur les Tardigrades, et sur leur propriete de revenir 

 a la vie (1842). draws from his own fine experiments the 

 folio wing conclusions: Rotiferse come to life, i. e. pass 

 from a motionless state to a state of motion, after having 

 been exposed to temperatures of 19. 2. Reaumur below, and 

 36 Reaumur above, the freezing point; i. e. from 11. 2 to 

 113.0 Fah. They preserve the capability of apparent 

 revivification, in dry sand, up to 56.4 R. (158.9 Eah.) ; 

 but they lose it, and cannot be excited afresh, if heated in 

 moist sand to 44 only (131.0 Pah.) Doyere, p, 119. 

 The possibility of revivification or reanimation is not pre- 

 vented by their being placed for twenty-eight days in baro- 

 meter tubes in vacuo, or even by the application of chloride 

 of lime or sulphuric acid (pp. 130-133). Doyere has 

 also seen the rotiferse 'come to life again very slowly after 

 being dried without sand (desseches a nu), which Spallan- 

 zani had denied (pp. 117 and 129). "Toute dessiccation 

 faite a la temperature ordinaire pourroit souffrir des objec- 

 tions auxquelles Temploi du vide sec n'eut peut-etre pas 

 completement repondu : mais en voyant les Tardigrades 

 perir irrevocablement a une temperature de 44, si leurs 

 tissus sont penetres d'eau, tandis que desseches ils sup- 

 portent sans perir une chaleur qu'on peut e valuer a 96 



