ILLUSTRATIONS (3). YITAL TENACITY OF INFUSORIA. 241 



remarkably careful and experienced observer, Doyere,* draws 

 the following conclusions from his beautiful experiments: 

 that Rotifera revive, i. e. pass from a motionless state to one 

 of motion, after being exposed to a cold of 11°. 2 Fahr., 

 or to a heat of 113° Fahr. ; that they preserve the property of 

 reviving in dry sand up to a temperature of 1 59° Fahr. ; but 

 that they lose this property and remain immoveable if warmed 

 in moist sand to 131° Fahr. only;f and that the possibility of 

 this so-called revivification is not prevented by their being 

 exposed to desiccation for twenty-eight days in barometric 

 tubes, in vacuo, even should chloride of lime or sulphuric acid 

 be employed. J 



Doyere has also seen Rotifera slowly revive after 

 being dried without sand, (desseches a. nu,) a fact which 

 Spallanzani denies. § "Desiccation conducted in an ordinary 

 temperature might be open to many objections which are 

 not perhaps wholly obviated by the employment of a dry 

 vacuum ; but when we observe that the Tardigrades irrevoc- 

 ably perish in a temperature of 131° Fahr. if their tissues are 

 permeated with water, whereas they can, when dried, support 

 a temperature that may be estimated at 248° Fahr., we are 

 disposed to admit that the sole condition required for animal 

 revivification is the perfect integrity of organic structure and 

 continuity." 



In like manner, the sporules, or germinating cells of cryp- 

 togamic plants, which Kunth compares to the propagation of 

 certain phanerogamic plants by buds (bulbillaB), retain their 

 power of germination in the highest temperature. Accord- 

 ing to the most recent experiments of Payen, the sporules of 

 a small fungus (O'idium aurantiacum), which invests the crumb 

 of bread with a reddish feathery coating, do not even lose 

 their vegetative powers by being exposed in closed tubes 

 for half an hour to a temperature of 183° to 208° Fahr. before 

 being strewn on fresh, unspoilt .dough. May not the newly 

 discovered and wonderful monad (Monas prodigiosa), which 

 causes blood-like spots in mealy substances, have been mixed 

 with this fungus ? 



* See his Memoire sur les Tardigrades et sur leur propriete de 

 revenir a la vie (1842). 

 + Doyere, Op. cit. p. 119. 

 % Doyere, Op. cit. pp. 130—133. 

 § Doyere, Op. cit. pp. 117 and 129. 



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