THE DOCTRINE 01' CONTAGIUM VIVUM. 31] 



cess of filtration is very slow ; it takes two or three days to 

 charge the flask. When a sufficiency has come over the ap- 

 paratus is removed and placed on a shelf for a few days until 

 the pressure inside and outside the flash is equalised. The 

 vulcanite cork is then withdrawn, and the exit-tube is 

 separated and sealed in the flame of a lamp. In this way^ 

 you obtain a sterilised flask charged with the filtered organic 

 liquid, and protected from outside contamination by a plug 

 of cotton -wool. Preparations obtained in this way, if due pre- 

 caution liave been used in the manipulation, remain per- 

 manently unchanged ; organisms do not appear in them, and 

 decomposition does not ensue. 



The third set of preparations are in some respects the most 

 significant of the three. They consist of organic liquids 

 which have been simply removed from the interior of tlie 

 living body, and transferred, without extraneous contami- 

 nation, into purified glass vessels. I will not detain you 

 with the methods employed to obtain them; it is sufficient 

 to say that, by the use of proper precautions, it is possible 

 to convey blood, pus, urine, ascitic fluid, pleuritic eflfusion, 

 blister serum, or the contents of an egg into sterilised glass 

 vessels without contact with any infecting agency. Prepara- 

 tions thus obtained are exhibited in these flasks ; they are 

 protected from air-dust by a simple covering of cotton-wool. 

 All of them are absolutely free from organisms and from any 

 signs of decomposition. 



What meaning can we attach to these preparations ? You 

 all know that liquids and mixtures such as these speedily 

 decompose and swarm with organisms Avhen left to them- 

 selves exposed to the air. They are of most varied compo- 

 sition, and the most apt of all known substances to breed 

 bacteria and to become decomposed. They have been ex- 

 posed to the most favorable conditions in regard to warmth, 

 moisture, and air. Many of them have been in my pos- 

 session several years, and all of them for several months, yet 

 they are wholly barren and without sign of decomposition. 

 I venture to say that these preparations substantiate in a posi- 

 tive maimer the proposition with which we started; namely, 

 that orrjanic inatter has no inherent power of generating hac- 

 teria and no inherent power of passhig into decomposition. 



A second proposition is likewise established by these pre- 

 parations ; namely, that bacteria are the actual agents of 

 decomposition. 



In all these preparations, the absence of bacteria coincides 

 with the absence of decomposition. If I were to cause bac- 

 teria to appear in them, either by purposive infection or by 



