58 
POPULAR SCIENCE REYIEW. 
tion of it from the watch-glass, and diluted it with a solution of 
potash, co.jsisting of 5 parts of potash in 100 of water. As 
soon as I perceived a globule evidently organised under the 
microscope, I drew it. This is how fig. 4 was drawn.” * This 
description leaves it uncertain whether an exact copy was taken 
of any portion of the field of the microscope, and, therefore, 
wliether the figure represents the exact number of corpuscles 
present, and their relation to each other. It only gives their 
Fig. 6. Fig. 7. Fig. 8. Fig. 9. Fig. 10. 
Exact copies of the figures given by M. Pasteur of tlie dust he collected on gun- 
cotton, magnified 180 diameters. These should be compared with fig. 1, magnified 
800 diameters, showing what is seen to take place when infusoria are forming. 
Fig. 10, scale of one-hundredth of a millimetre. 
form. But, assuming that the same kind of demonstration was 
made in each case, we have the relative numbers of these bodies 
taken from the gun-cotton in fig. 6. Fig. 7 is another demon- 
stration of the same after the addition of an aqueous solution of 
iodine. Fig. 8 represents the organised corpuscles associated 
w’ith amorphous particles obtained on June 25 and 26, 
1860; fig. 9, the dust of an intense fog in the month of Feb- 
ruary 1861. In all these demonstrations he admits the organ- 
ised corpuscles are comparatively scarce, because, he observes 
(p. .31), it is frequently necessary to change the field in order 
to see one of them, whilst at other times several could be seen 
together. 
M. Pasteur thinks that these drawings indicate the number of 
organised corpuscles that may be arrested in a small mass of 
cotton through which 1,500 litres of air, in one of the less- 
frequented streets of Pari.s, have passed in twenty-four hours, 
about three or four yards from the ground. These he estimates 
at several millions in a btre (p. 29). 
Now, it must 1 e remembered that M. Pasteur is a chemist, 
and it will be admitted by every histologist that no method 
could be more unsatisfactory for determining either the nature 
or the number of the corpuscles than the one he adopted. The 
solution of the cotton in ether, the freipient soakings in water, 
ti e defecation, and then the addition of a solution of potash, 
must completely alter the character of any living corpuscles in 
* Annales dee Sciences Naturelles,” 4me sdrie, tome xvi. p. 25. 
