160 
noticed. After this dust from the atmosphere had been 
kept quiet for three or four days, animalculse made their 
appearance in considerable numbers, the monads being the 
most numerous. Amongst these were noticed some com- 
paratively large specimens of paramecium aurelia, in 
company with some very active rotiferse ; but after a few 
days the animal life rapidly decreased, and in twelve days 
no animalculae could be detected. 
Hairs of Animals . — Very few of these were noticed, with 
the exception of wool; of this both white and coloured 
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, 
and as there were 150 drops, the sum total reaches the 
startling number of 37£ millions, and these, exclusive of 
