212 Merkel Henry Jacobs 



invariably killed. He considered this result to be due to the inju- 

 rious effect of the air on the dried animals, the sand protecting 

 them from its action. He made many other interesting observa- 

 tions, for example, on the effect of high temperatures on animals 

 in different degrees of desiccation, on the number of times they 

 may be dried without being killed and the effect on them of vari- 

 ous chemical substances. Unlike Leeuwenhoek he believed that 

 the rotifers could endure the withdrawal of the last traces of water 

 from their bodies. He was able to revive them after subjecting 

 them while in the dried state to the desiccating action of high 

 temperatures and the vacuum. There was no doubt in his mind 

 that the process of desiccation caused an actual stoppage of the 

 life processes and that the animals in the dried condition were to be 

 considered as dead. He entitled his paper, "Observations and 

 experiments on certain marvelous animals which the observer 

 can at his will make pass from death to life." 



Spallanzani's work naturally excited great interest and gave 

 rise to much discussion. The statement that animals could be 

 brought back to life after being dead for a time could not be 

 allowed to pass unchallenged by the physiologists of the day and 

 many heated controversies arose between those who supported 

 Spallanzani and those who opposed him. Among those who 

 engaged in the discussion may be mentioned such distinguished 

 naturaHsts as Haller, Cuvier, Oken, Humboldt, Lamarck, Tre- 

 viranus, and Johannes Miiller. The controversies for the most 

 part, however, were carried on on purely theoretical grounds and 

 had little experimental evidence to back them. From the time of 

 Spallanzani to the time of Doyere, a period of sixty years, although 

 the question continued to be one of the most discussed in the whole 

 realm of physiology, practically no new facts were added to our 

 knowledge of the subject. 



On the whole, the opponents of Spallanzani seemed to gain the 

 upper hand. This was largely due to the apparently convincing 

 arguments advanced by two men, Ehrenberg in Germany and 

 Bory St. Vincent in France. Both of these workers not only 

 denied that dead rotifers could be brought back to life but asserted 

 that recovery after true desiccation was impossible. The unde- 



