AIR BENEATH THE MICROSCOPE. 
165 
Among recent writers who have devoted much time and at- 
tention to the influences of atmospheric contagion, unquestion- 
ably he who takes the highest rank is Mr. Blackley.* It is to 
be regretted that he has confined his attention merely to one 
class of disease alone. But in compensation for this we have 
the very extended nature of his inquiries and the elaborate re- 
searches that he has made. Mr. Blackley considers that he 
has proved that hay-fever is decidedly caused by the patient’s 
inhalation of air containing a considerable quantity of pollen ; 
that this pollen adheres to the membranous lining of the 
larynx and air-passages and the nasal lachrymal membranes, and 
thus causes the excessive secretion which is so troublesome an 
effect of these diseased conditions. And whatever view we may 
take of this part of his book, he has by the most ingenious 
microscopical contrivances proved beyond the slightest question 
that a very large amount of pollen is inhaled from the air, at 
all events in certain seasons. 
Dr. Beale, than whom there is no one of profounder experi- 
ence in microscopic research, has given his testimony in favour 
of the view that the atmosphere contains the germs at least of 
certain diseases. He examined the infected air of the cattle- 
plague period, which had been obtained by Mr. Crookes, F.R.S.,, 
and he found that the fluid obtained from saturating the 
cotton-wool exposed to the air, in glycerine, gave undoubted, 
evidence of fungus sporules. And he even goes so far as to 
throw out the suggestion that malarial poison may possibly be a 
degraded type of the bioplasm of lower animals and plants. 
Another observer in this very wide field is Dr. Salisbury* 
of the United States of America. And his researches were 
very accurately made, and lead to conclusions most favourable 
to those who believe in the atmosphere’s swarming with micros- 
copic life, and in the possibility of disease being so carried 
from one place to another. Dr. Salisbury’s! observations were 
made in the year 1862, when there was a great prevalence 
of intermittent and remittents fevers in the low valleys of the 
Ohio and Mississippi. These maladies appeared, says Dr. Cun- 
ningham, in the month of May, and were very prevalent in July 
and August. The season was a very wet one up to the end of 
June, but there was no rain in July, August or September, and 
with the cessation of the rain the increase in the number of 
cases of fever occurred. Dr. Salisbury in the first place ex- 
amined saliva and mucus from the mouth and naves of the 
sufferers, and detected the presence of large numbers of zoo- 
* “ Experimental Researches on the Causes and Nature of Catarrhus 
iEstivus ” (Hay-fever, or Hay-asthma). By C. H. Blackley, M.R.C.S., 1872. 
t “American Journal of Medical Science,” April 1866. 
