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elusive. If it be allowed to stand for a few days (about a 
week is enough), it will then show itself more decidedly 
by becoming the abode of small animals. These are rather 
to be styled animalcules, and very small ones certainly, 
unless a considerable quantity of liquid be obtained : they 
may be seen with a good microscope. Animalcules are now 
generally believed to come from the atmosphere and to 
deposit themselves on convenient feeding places ; that is, 
they only appear where there is food or materials for their 
growth, and they prove of course the existence of that con- 
tinuation of elements necessary for organic life. At the 
same time their presence is a proof of decomposing matter, 
as their production is one of the various ways in which 
organized structure may be broken up.” 
“I mentioned some time ago that I had got a quantity of 
organic matter from the windows of a crowded room, and 
I have since frequently repeated the experiment. This 
matter condenses on the glass and walls in cold weather, 
and may be taken up by means of a pipette. If allowed to 
stand some time it forms a thick, apparently glutinous mass; 
but when this is examined by a microscope, it is seen to be 
a closely matted confervoid growth, or in other words, the 
organic matter is converted into confervse, as it probably 
would have been converted into any kind of vegetation that 
happened to take root. Between the stalks of these confervse 
are to be seen a number of greenish globules constantly 
moving about, various species of Volvox, accompanied also 
by monads many times smaller. When this happens the 
scene is certainly lively and the sight beautiful, but before 
this occurs the odour of perspiration may be distinctly per- 
ceived, especially if the vessel containing the liquid be 
placed in boiling water. 
“If air be passed through water a certain amount of this 
material is obtained, but I have found it difficult to pass a 
