LEEUWENHOEK AND HIS ‘‘ LITTLE ANIMALS” 
only be discerned by means of surpassing good magni- 
fying-glasses, or telescopes; and these creatures, they 
say, have been seen in Rome.’ For my part, notwith- 
standing the manifold observations I have carried out to 
this end, I have as yet seen no lesser animalcules moving 
in the air than those which are so big that you can 
readily make them out with the naked eye. The very 
little particles which I have commonly found in the air, 
and which are there in motion, are all earthy particles, 
which are given off by (so to speak) “ dustsome ” ’ things. 
For you can’t tear a sheet of paper apieces, but what 
more than a thousand very tiny fibres break off, and these 
so light withal, that they can’t easily fall upon the earth, 
owing to the motion that is in the air: you can’t draw a 
comb through the hair of your head, but what various 
very little particles, which lie or are stuck upon every 
hair, are set loose and moved in the air; not to mention 
the wearing away and the breaking off which each several 
hair suffers in the act of combing. Nor can you so much 
as rub your hands together, when they are dry, nor stroke 
your face, without thereby imparting a multitude of tiny 
scaled-off particles to the air; and ’tis even so with wood, 
earth, smoke, etc. Such particles as these would seldom 
fall upon the earth, so long as they be in the sun’s rays, 
or in a light breeze; but on coming out of the sun’s rays, 
and out of the strong motion of the air, they sink towards 
the earth: and these little bits of dust thus lying still, 
and not sticking to larger particles that are heavier, may 
again be set a-moving by the mere motion of the air, or 
the sun’s rays. From what observations I have made 
hereon, I can’t say I ever saw, among the rest, two bits 
of dust that exactly agreed with one another in shape. 
But I'll not deny that there can be, in the air, any living 
creatures which are so small as to escape our sight; I say 
1 
2 
A rumour, I take it, of the imaginative work of Athanasius Kircher. 
stofligte MS. lL. here invents a word meaning “ apt to form dust.” 
