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Show 256 PHYSIOGNOMY OF PLANTS. tions have been more exact and have had to undergo 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 extremely careful and experienced observer, Doyere, in his Memoire sur les Tardigrades, et sur leur propriete de revenir a Ia vie (1842), draws from his own fine experiments the following conclusions : Rotiferre 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 o .2 to 113°.0 Fahr. They preserve the capability of apparent revivification, in dry sand, up to 56°.4 R. (158°.9 Fah.)j 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. 130-133). Doyere has also seen the rotiferre come to life again very slowly after being dried without sand (desseches a nu), which Spallanzani had denied (pp. 11 '7 and 129). "Toute dessiccation faite a la temperature ordinaire pourroit souffrir des objections auxquelles l'emploi 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 supportent sans perir une chaleur qu'on peut evaluer a 96° Reaumur, on doit etre dispose a admettre que la revivification n'a dans !'animal d'autre condition que l'integrite de composition et de connexions organiques." In the same way, in the vegetable kingdom, the sporules of cryptogamia, which Kunth compares to the propagation of certain phrenogamous plants by buds (bulbillre ), retain their germinating power in the highest temperatures. According to the most recent experiments of Payen, the sporules of a minute fungus (Oi:dium 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°.5 Fahr. ), before being strewed on fresh, perfectly |