94 THE POPULAR SCIENCE MONTHLY. 



To obviate the objection of a possible change by heat, in a mys- 

 terious and undefined principle, different from germs, but whose pres- 

 ence in the air was necessary to the production of infusoria, Schultze 

 caused the renewed air to pass through energetic chemical reagents, 

 such as concentrated sulphuric acid. He half filled a glass vessel 

 with distilled water containing various animal and vegetable sub- 

 stances ; then stopped the vessel with a cork through which passed 

 two bent tubes, and exposed the apparatus thus arranged to the tem- 

 perature of boiling water. Then, while the vapor was still escaping 

 through the tubes, he adapted to each of them a Liebig's bulb appa- 

 ratus, one containing concentrated sulphuric acid, and the other con- 

 centrated caustic potash. The high temperature must necessarily 

 have destroyed every living thing, all the germs that might happen 

 to be in the inside of the vessel, or of its appendages, and the commu- 

 nication from without was intercepted by the sulphuric acid on one 

 side and the potassa on the other. Nevertheless, it was easy to 

 renew, by aspiration at the end of the apparatus which contained the 

 potassa, the air thus inclosed, and the fresh quantities of this fluid 

 which were introduced could not carry with them any living germ, 

 for they were forced to pass through a bath of concentrated sulphuric 

 acid. M. Schultze placed the apparatus thus arranged at a well- 

 lighted window, side by side with an open vessel, which contained an 

 infusion of the same organic substances ; then he was careful to renew 

 the air in his apparatus several times a day for more than two months, 

 and to examine with the microscope what took place in the infusion. 

 The open vessel was soon found filled with vibrios and monads, to 

 which were soon added polygastric infusoria of a larger size, and even 

 rotifers ; but by the most attentive observation he could not discover 

 the least trace of infusoria, confervae, or mildews, in the infusion con- 

 tained in the apparatus. 



The latest researches of Schroder and Von Dusch (1854-1859) tend- 

 ed to raise another objection, the possible change in a special prin- 

 ciple in the air, by a reagent as energetic as sulphuric acid. Guided 

 by the experiments of Loewel, who ascertained that common air, when 

 it had been previously filtered through cotton, was unfit to cause the 

 crystallization of supersaturated solutions of sodium sulphate, they 

 placed one of the tubes of Schultze's apparatus in communication with 

 a tube 1.18 inch in diameter, and from 19.68 to 23.62 inches in length, 

 tilled with cotton-wool. The other tube was connected with an aspi- 

 rator. 



When the liquid, the interior of the flask, and the tubes, had been 

 deprived of air by boiling, the apparatus was removed to its place, 

 and the aspiration continued night and day. The two observers thus 

 proved that meat, to which water had been added, the wort of beer, 

 urine, starch, paste, and the various materials of milk taken separate- 

 ly, remained intact in the filtered air. On the contrary, milk, meat 



