HISTORICAL. 



II 



cell-substance, the oxygen of the air and conducting it to the substances 

 undergoing fermentation, resulting in the splitting up of sugar into alcohol 

 and carbonic acid gas. 



The question of spontaneous generation was again discussed with renewed 

 energy. The belief that larger animals could originate de novo was quite 

 generally abandoned, but it was very persistently argued that micro-organisms, 

 maggots and a few other very small animals could thus develop. Bastian 

 was perhaps the leader in the arguments in favor of spontaneous generation, 

 opposed by Schwann, Pasteur, and others. Schroeder and von Dusch dem- 

 onstrated that decay could be prevented by boiling and supplying air that 

 had been filtered through cotton. Pasteur (1862) used bent tubes to supply 

 air to the previously sterilized (by heating) substance, as shown in Fig. 3. 



Fio. 3. — Flask, containing an organic substance, a, hermetically closed by means 

 of a stopper, b. The bent tube is open at e, admitting air. Dust and microbes lodge 

 at the bends d and c. 



The microbes in the air passing through the tube are deposited (by gravity) 

 in the lower bends of the tube. Those favoring the theory of spontaneous 

 generation nevertheless continued their arguments. It was pointed out that 

 changes of decay took place in eggs, in internal tissues and organs of the 

 dead as well as in the living, etc., where, it was supposed, microbes could 

 not possibly have access. However, further convincing experiments 

 gradually silenced all opposition. Bastian and a few followers took practi- 

 cally their last stand in 1875, and since that time no scientist of repute has 

 ever argued in favor of spontaneous generation, though the question of the 

 primal origin of living things remains unanswered. 



Vaccination as a protection against virulent small-pox was practised 

 early in the eighteenth century in Turkey and other Oriental countries, and 

 was introduced into Europe via England through the influence of Lady 

 Mary Wortley Montagu. A. von Humboldt states that the Mexicans 

 practised vaccination at a very early period. This early vaccination mate- 



