Effects of Desiccation on the Rotifer 211 



that he discussed the subject on his own account. Needham's 

 discovery excited considerable attention but was for the most 

 part received with increduhty. That Hving organisms could be 

 dried and after remaining apparently lifeless for a time be caused to 

 "take life" by the application of water seemed so incredible 

 to the scientists of the day that they preferred either to deny the 

 animal nature of the worms altogether, caUing them "filaments 

 animes, " " fibres mouvantes " or " etuis pleins de globules mobiles " 

 which were started into movement by the imbibition of water or 

 to assert that they arose by spontaneous generation. It was not 

 until the time of Fontana (1771) and Roffredi (1775) ^^^^ ^^^ ^^^~ 

 mal nature of these anguillulids was established beyond all doubt. 



In the meantime other men were making similar observations. 

 Among the earhest of these may be mentioned Trembley (1747), 

 Baker (1753), Schaeffer (1755), Ginnani (1759), Ledermiiller 

 (1759), Fontana (1768), Goze (1772), Corti (1774), Muller 

 (1775) and Roffredi (1775). The list of the animals capable of 

 enduring desiccation was also increased during this period. Leder- 

 miiller in 1759 had observed the revival of "paste eels," Fontana 

 in 1768 of Gordius, and Spallanzani in 1776 of tardigrades and 

 the anguilluHds found in the dust of roofs. Later observers added 

 several new forms and increased the list of rotifers and tardigrades 

 which show this peculiarity. 



The history of our exact knowledge of the phenomenon of sus- 

 pended animation dates from the publication in 1 776of Spallanzani's 

 "Opuscoli di Fisica Animale e Vegetabile. " The section of this 

 work relating to the desiccation of animals is a model of scientific 

 research. Spallanzani, unlike most of his contemporaries, tested 

 his theories by actual experiments and these experiments were 

 often carried out with great care and considerable ingenuity. 

 If other workers had used the same amount of care the subject 

 would be in a far less confused state than it is at the present day. 

 Spallanzani first repeated the experiments of Leeuwenhoek and 

 made the observation, which has been confirmed by a number of 

 subsequent workers on the subject, that rotifers can recover their 

 activity after a period of drying only when a certain amount of 

 sand or moss is present; when dried on a clean glass slide they are 



