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spores, animalcules, diatoms, desmids, cells and filaments of 
algae, and spores of fungi. The only bodies which were of con- 
stant occurrence, and generally in great abundance, were small 
©blong cellules, which were either isolated or grouped in masses. 
They had a distinct nucleus contained within a smooth cellular 
envelope. He decided that they were algal cellules chiefly 
resembling palmellae, and found that they only occurred in 
malarial districts. 
He then proceeded to look for them in the air, his method 
of procedure being to suspend pieces of glass over marshy pools 
and swampy places. The glasses were set in the evening and 
removed before sunrise next morning. Drops of water were 
found adhering to their under surfaces and containing nu- 
merous cells of various kinds, but none resembling the peculiar 
palmelloid cellules previously alluded to. These were, how- 
ever, constantly present in considerable numbers on the upper 
surfaces. His next step was to endeavour to ascertain from 
what source they were derived ; and, after a considerable 
amount of fruitless search, he discovered it in a sort of greyish 
mould covering the recently exposed surfaces of cracks in rich 
prairie ground, which had been recently dried and was much 
broken up by the feet of cattle. On suspending glasses over 
places covered by this mould, he found numbers of the cellules 
in the fluid on their under surfaces. 
In following out these experiments, Dr. Salisbury came to 
the conclusions that cryptogamic spores rise chiefly during the 
night and fall shortly after sunrise ; that the height to which 
the cellules in question rose was 30 to 100 feet from the sur- 
face ; that none of them were present during the day ; that 
•covering the soil to a depth of several inches with straw or 
quicklime prevented their rise ; that a stay of fifteen minutes 
in places in which they abounded gave rise to dryness and 
febrile heat of the throat coincident with their presence in the 
pharyngeal mucus ; and that persons exposed to their inhala- 
tion, even far from their original source, under entirely dif- 
ferent circumstances, in non-malarial districts, suffered from 
attacks of fever as a consequence. 
We hardly think that there could be more convincing evi- 
dence than this. But then it has to be borne in mind that the 
district under examination was somewhat an exceptional one. 
The observations of Dr. Swayne and Mr. Brittan, though 
they were called in question by the subsequent Report of the 
Royal College of Physicians, similarly give evidence in favour 
of this view of the matter. They go to show that in cholera 
times there exist in the atmosphere peculiar cells, whose struc- 
ture, as far as they could see, was identical with that of the 
well-known annular cells from choleraic fecal discharges. They 
