FROM THE AIR OF MANCHESTER. 273 



noticed. After this' dust from the atmosphere had been 

 kept quiet for three or four days, animalcula made their 

 appearance in considerable numbers, the monads being the 

 most numerous. Amongst these were noticed some com- 

 paratively large specimens of Pai^amecium aurelia, in com- 

 pany with some very active Rotifera ; but after a few days 

 the animal life rapidly decreased, and in twelve days no 

 animalcula could be detected. 



Hairs of Animals. — Very few of these were noticed, 

 with the exception of wool; of this both white and co- 

 loured specimens were mixed up along with the filaments 

 of cotton. 



After each examination as much of the drop of water as 

 could be collected by the pipette was returned to the 

 bottle, in order to ascertain if any new development of 

 animal or vegetable life would take place, and the stopper 

 of the bottle was replaced as quickly as possible to prevent 

 the admission of the particles from the air in the room ; 

 and I am tolerably certain that the objects named in this 

 paper are those which the bottle contained when Dr. Smith 

 brought it to me. 



The particles floating in the atmosphere will differ in 

 character according to the season of the year, the direction 

 of the wind, and the locality in which they are collected, 

 and, as might be expected, are much less in quantity after 

 rain. 



The small amount of fluid now remaining in the bottle 

 emits the peculiar odour of mildew ; and at present the 

 fungoid matter appears inactive. 



For the purpose of obtaining a rough approximation of 

 the number of spores, or germs of organic matter contained 

 in the fluid received from Dr. Smith, I measured a quantity 

 by the pipette and found it contained 150 drops of the size 

 used in each examination. Now, I have previously stated 

 that in each drop there were about 250,000 of these spores; 



SER. III. VOL. IV. T 



