262 THE BEGINNINGS OF LIFE. 



remarkable c Memoire sur le developpement et la duree 

 de la vie des infusoires,' endeavoured to establish the 

 fact that the generation of infusoria takes place normally 

 by means of eggs, and that their multiplication by this 

 process, in combination with that by fission, was suffi- 

 cient to account for their numbers in organic infusions. 

 Schultze and Schwann, however, sought to undermine 

 the position of the heterogenists by adducing experi- 

 mental proofs in support of the panspermic doctrine. 

 Schultze alleged that no organisms of any kind were 

 produced in a fermentable solution which had been 

 raised to a temperature of 212 F., provided the air 

 which was allowed access to this fluid had been pre- 

 viously made to traverse concentrated sulphuric acid, 

 so as to free it from all possible germs ; and Schwann 

 stated that the experiments were, with certain reser- 

 vations *, marked by the same sterility when calcined 

 or highly heated air only was allowed access to the 

 vessel containing the previously boiled solution of 

 organic matter. These assertions, which have been 

 subsequently disproved, had an immense influence at 

 the time against the doctrine of heterogeny. 



Though in the intervening years the subject was still 

 worked at from time to time, yet almost a new epoch 

 in the controversy may be said to have commenced 



1 His results were conflicting and contradictory whilst dealing with 

 materials which underwent the alcoholic fermentation. Sometimes 

 organisms were to be met with in such solutions in spite of all his 

 precautions. 



