A HISTORY OF SCIENCE 



ovum and spermatozoon. Unfortunately he misin- 

 terpreted the part played by the spermatozoa in be- 

 lieving that their surrounding fluid was equally active 

 in the fertilizing process, and it was not until some 

 forty years later (1824) that Dumas corrected this 

 error. 



THE CHEMICAL THEORY OF DIGESTION 



Among the most interesting researches of Spallanzani 

 were his experiments to prove that digestion, as car- 

 ried on in the stomach, is a chemical process. In this 

 he demonstrated, as Rene Reaumur had attempted to 

 demonstrate, that digestion could be carried on outside 

 the walls of the stomach as an ordinary chemical re- 

 action, using the gastric juice as the reagent for per- 

 forming the experiment. The question as to whether 

 the stomach acted as a grinding or triturating organ, 

 rather than as a receptacle for chemical action, had 

 been settled by Reaumur and was no longer a question 

 of general dispute. Reaumur had demonstrated con- 

 clusively that digestion would take place in the stom- 

 ach in the same manner and the same time if the sub- 

 stance to be digested was protected from the peristalic 

 movements of the stomach and subjected to the action 

 of the gastric juice only. He did this by introducing 

 the substances to be digested into the stomach in tubes, 

 and thus protected so that while the juices of the 

 stomach could act upon them freely they would not 

 be affected by any movements of the organ. 



Following up these experiments, he attempted to 

 show that digestion could take place outside the body 

 as well as in it, as it certainly should if it were a purely 



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