124 kaxsas Academy of Science. 



had been previously prepared and was now fairly milky by reason of its swarms of 

 active bacteria, a dumb-belled micrococcus. The filter remained in this solu- 

 tion, a drop of which examined under the microscope showed myriads of micro- 

 cocci, from 3:15 p. m. November 3, until 8:30 a. m. November 4. 



November 4th, at 8:30 a.m., the filter was removed from the Pasteur solution, and 

 with a delicate sterilized pipette four drops of the filtered solution were taken from 

 the filter and introduced into turnip infusion tube 11 by removing the cotton plug 

 and cover, and quickly and carefully replacing them. Same with turnip infusion 

 tube 17, and with hay infusion tubes (only three drops each in hay tubes). All of 

 these tubes were perfectly clear, and showed no signs ( turbidity) of the presence of 

 bacteria. Two drops each of the unfiltered Pasteur solution, containing micrococci, 

 were introduced into tubes 6 and 12 (one hay and one turnip). These tubes were 

 both clear, and showed no change since being charged. The filter was then replaced 

 in the bacterial solution, and at 3 p.m. one hay flask and one turnip flask (neither 

 flask showing any change since day of charging) were inoculated with a drop or two 

 of the filtered solution, and placed in a beaker numbered 31. The introduction of 

 the filtered solution into the flasks was made by breaking off the tips of the flasks' 

 stems with sterilized forceps, and using an extremely fine sterilized pipette which 

 could be inserted in the stem of each flask. Two other flasks — a hay and a turnip — 

 were inoculated with the unfiltered solution and put into a beaker numbered 32. 

 Ten drops of the filtered solution were successively examined with a microscope, 

 using a magnification of about 500 diameters, and no bacteria were found. The re- 

 mainder of the filtered solution was put into two sterilized tubes which were loosely 

 plugged with cotton. 



During the afternoon the filter was resterilized and suspended in unsterilized 

 turnip infusion (from 29), which was turbid with bacteria. Tubes and flasks were 

 inoculated as follows (all about 3 p.m.): 



With filtered infusion, tubes 7 (with three drops), 13 (with three drops), flasks 

 13+, 7 + . 



With unfiltered infusion, tubes 9 (with two drops), 14 (with two drops). 



Several drops of the filtered infusion were examined by Mr. Stevens, assistant in 

 botany, and were reported by him to contain a few, two or three to the drop, bac- 

 teria which did not move, and were apparently lifeless. 



All of these tubes and flasks were kept in a room having a fairly equable tem- 

 perature of about 32 C The room had not been used recently, and though dirty 

 and in disorder, the atmosphere was presumably fairly free from bacterial or other 

 fungoid spores. The room was- kept locked and the tubes sat on a table in the 

 middle of the room and at no time of the day in direct sunlight. There were no 

 changes of temperature tending to cause strong air-currents either in the tubes or 

 about them. Observations were made often, but the ones here recorded show the 

 changes noted in the fluids, and the incidents connected therewith, up to date of this 

 writing. Each tube and flask is considered separately, and is referred to by number. 

 Those prepared tubes and flasks not referred to were used in other experiments inci- 

 dent to the ones here described : 



Tube No. 4 : Charged Oct. 30, 12:30 p. m., with sterilized hay infusion; closed 

 with cotton. 

 Nov. 4, 9 a. m., clear ; no change ; inoculated with three drops 

 filtered Pasteur's solution, which before filtering swarmed with 

 dumb-bell micrococci. 

 Nov. 5, 3 p. m., clear ; no change. 

 Nov. 10, 2 p. m., clear ; a small patch of penicillium on surface. 



