244 ON THE RESUSCITATION OF WHEEL ANIMALCULES. 



I was desirous of ascertaining if a drying, under the same circum- 

 stances, of shorter duration, would be followed by a return to life ; but 

 I have seen that complete desiccation for five minutes was enough to 

 deprive them of life, which could not be restored ; and if a privation of 

 water for the shortest time did not kill them, it probably arose from 

 a small portion of moisture being retained under the envelope. 



Being thus convinced of the impossibility of their resuscitation when 

 they have dried without any other protection than that of their own 

 envelope, I was anxious to ascertain whether they would resuscitate 

 when dried in a vase of the sand found at the bottom of the pond which 

 they inhabited. I accordingly placed a number of these animalcules 

 fixed on the same twig, in a watch-glass, and covered the whole with a 

 vase, leaving them to dry. In about twenty-four hours, the whole 

 appearing to be dry, I poured some water upon them, and when well 

 soaked, I cautiously lifted up the twig with the animalcules, and placed 

 it in some pure water in another watch-glass, in order to examine it 

 with the microscope. I was not able, however, to perceive in this case 

 any resuscitation, though I kept them during eight days in the water. 



Astonished at these results, which deceived my strongest expecta- 

 tions, I began to imagine that the sand of the gutters imparted some 

 peculiar virtue to the animalcules to enable them to resuscitate. I 

 therefore took some of this sand, which swarmed with Leeuwenhoeck's 

 wheel animalcule, (Ezechielina Miillerii, Bory,) and dried in it a 

 number of my wheel animalcules. When I examined it in about 

 twenty-four hours afterwards, none of them showed any signs of life, 

 although the same sand contained a number of Leeuwenhoeck's 

 wheel animalcules and tile eels, (Anguilles des Tuiles,) which had 

 resuscitated. I conclude, therefore, that the wheel animalcule of 

 Leeuwenhoeck is the only one of the rotiferce known, which is endowed 

 with the faculty of resuscitation. 



REMARKS ON THE RESUSCITATION OF THE WHEEL 



ANIMALCULES. 



BY COLONEL BORY DE ST. VINCENT. 



All the wheel animals live exclusively in water, drying speedily 

 kills them, and it is difficult to imagine, on taking into account the 

 complication of their organs, of their heart, and their respiratory gills, 



