150 



Mr. W. N. Hartley on the 



[Feb. 8, 



No. 2. Opened August 29th, 1871. Kept over ten months and a half. 

 Nothing unusual was seen in the liquid; it smelt perfectly fresh, and looked 

 quite bright and clear. 



No. 3. Opened July 19th, 1871. Kept nearly nine months. The liquid 

 was quite fresh and clear. There were seen two or three minute bodies, too 

 small for any definite observation to be made concerning their form. They 

 had apparently an irregular rotatory slow motion, which continued ; and 

 careful observation led me to conclude it was only the Brownian move- 

 ment. This conclusion was afterwards confirmed. See F' 3. 



No. 4, T. Opened October 19th, 1870. Both Torula and mucors were 

 discovered in abundance after three weeks' exposure to the air. 



Liquids which, after prolonged preservation in sealed tubes, were exposed 

 to air filtered through cotton-wool, kept at a temperature q/'30 o -34 o C. 

 during the daytime, and not below 24° C. at night. 

 D'. No. 1. Examined on July 21st, and again September 7th, 1871. — 



The liquid was quite unchanged. Nothing found in it after a period of 



fifty-two days. 



No. 2. Examined August 22nd and September 8th. No trace of any 

 organism. Quite unaltered. Kept fifty-four days. 



No. 3. As the first sign of any change occurring in the solution is tur- 

 bidity, this tube was not submitted to microscopical examination. On 

 September 8th it was still perfectly clear to the eye, apparently quite un- 

 altered after more than a month. 



E'. No. 2. Opened July 19th, examined September 13th, 1871, after a 

 period of two months. Quite unaltered. 



F'. Examined after exposure to air for five weeks, from July 19th to 

 August 23rd, 1871. 



No. 3. The liquid smelt quite fresh, and was unaltered in appearance. 

 Only two of the minute particles previously mentioned were seen : they 

 were most certainly lifeless, and also for the most part motionless ; one was 

 seen to move with a current in the liquid, but the rotatory motions before 

 noticed did not occur. A most attentive examination for a length of time 

 was devoted to these bodies ; in size they could not have been larger than 

 0'00002 inch. The conclusion as to their being lifeless was borue out by the 

 fact that their small number (only five were seen) had not increased, though 

 under favourable circumstances for reproduction, even after a period of five 

 weeks. 



" No. 2. Sept. 13. Liquid quite unaltered. Kept nine weeks. 



Liquids which, after prolonged keeping without development of life, were 

 afterwards exposed to ordinary air at a temperature ranging between 

 24° C. and 34° C. Any pipette or glass rod placed in these liquids 

 had immediately before been heated to at least 200° C. 

 D". Examined July 18th, after exposure to the air four days. No. 1. 



The liquid was very turbid, and smelt very offensive ; it swarmed with 



