256 PHYSIOGNOMY OF PLANTS. 



tions have been more exact and have had to undergo stricter criti- 

 cism, iias 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 extremely careful and experienced observer, Doyere, in his 

 Memoire sur les Tardigrades, et sur leur propriete* de revenir a la 

 vie (1842), draws from hi^ own fine experiments the following con- 

 clusions : RotiferaB 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 Fahr. They preserve the capability of 

 apparent revivification, in dry sand, up to 56.4 R. (158. 9 Fah.); 

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

 to 44 only (131.0 Fah.) Doyere, p. 119. The possibility of 

 revivification or reanimation is not prevented by their being placed 

 for twenty-eight days in barometer tubes in vacuo, or even by the 

 application of chloride of lime or sulphuric acid (pp. 130133). 

 Doyere has also seen the rotiferse come to life again very slowly after 

 being dried without sand (desse"che*s k nu), which Spallanzani had 

 denied (pp. 117 and 129). "Toute dessiccation faite & la tempe"ra- 

 ture ordinaire pourroit souffrir des objections auxquelles Temploi du 

 vide sec n'eut peut-etre pas completement repondu : mais en voyant 

 les Tardigrades perir irre>ocablement k une temperature de 44, si 

 leurs tissus sont pe'netre's d'eau, tandis que desseche's ils supportent 

 sans p4rir une chaleur qu'on peut evaluer a 96 Reaumur, on doit 

 dtre dispose" & admettre que la revivification n'a dans T animal d'autre 

 condition que Fintegrite de composition et de connexions organiques." 

 In the same way, in the vegetable kingdom, the sporules of crypto- 

 gamia, which Kunth compares to the propagation of certain phgeno- 

 gamous plants by buds (bulbillae), retain their germinating power in 

 the highest temperatures. According to the most recent experiments 

 of Payen, the sporules of a minute fungus (Oidium aurantiacum), 

 which covers the crumb of bread with a reddish, feathery coating, do 

 not lose their power of germination by being exposed for half an 

 hour in closed tubes to a temperature of from 67 to 78 Reaumur 

 (182.75 to 207 6 .5 Fahr.), before being strewed on fresh, perfectly 



