72 
have found sulphuretted hydrogen, carburetted hydrogen, 
hydrogen, carbonic acid, nitrogen, hydrogen, ammonia, 
acetic acid, lactic acid, butyric acid, and numerous uncertain 
bodies having no activity, and utterly incapable of produc- 
ing those prodigious results that are found when that force 
begins to work which produces plague, small-pox, or black 
death.” 
I did not enter on Pasteur’s ground, — the action of organ- 
isms in producing fermentation. 
After these opinions and the detail of many facts one is 
mentioned which was the culminating point of the enquiry, 
and has led to a mode of collecting the organic particles of 
air, which I may call established. This word established is 
used because the experiment has been done by others. It 
is given in these few but plain words : “ The air of cow- 
houses and stables is to be recognised as containing more 
particles than the air of the street in which my laboratory 
is, and of the room in which I sit, and that it contains 
minute bodies, which sometimes move, if not at first, yet 
after a time, even if the bottle has not been opened in the 
interval. There is found in reality a considerable mass of 
debris with hairs or fine fibres, which even the eye, or at 
least a good pocket lens, can detect. After making about 
two dozen trials, we have not been able to obtain it other- 
wise. Even in the quiet office at the laboratory there 
seemed some indications.” 
“ I found similar indications in a cowhouse with healthy 
cows ; so I do not pretend to have distinguished the poison 
of Cattle Plague in these forms ; but it is clear that where 
these exist there may be room for any ferment or fomites 
of disease; and I do not doubt that one class is the poison 
itself in its earliest stage. It would be interesting to de- 
velope it farther.” 
I do not detail the examination made of the condensed 
air brought from a cowhouse by Mr. Crookes, nor do I detail 
