1901) MICROSCOPICAL JOURNAL. 5 
optical test to determine the purity of its atmosphere, a 
powerful ray of light being passed through the side win- 
dows. When viewed through the front window, this ray 
was visible as long as there were particles suspended in 
the atmosphere to reflect it. When the dust had com- 
pletely settled and the light ray was invisible because of 
the purity of the atmosphere, the tubes were cautiously 
filled with urine, beef broth, and a variety of animal and 
vegetable broths, great care being taken that in the ma- 
nipulation the pipette should not disturb the dust, Their 
contents were then boiled by submergence in a pan of hot 
brine placed beneath the chamber, in contact with the 
projecting ends of the tubes, and allowed to remain un- 
disturbed for days, weeks or months. In nearly every 
ease life failed to develope after the purity of the atmos- 
phere was established. 
The following extracts from Tyndall’s work will illus- 
trate how slowly the doctrine of spontaneous generatign 
was abandoned: ‘At a meeting of the Pathological So- 
ciety of London, held April 6, 1875, the ‘germ theory’ of 
disease was formally introduced as a subject for discus- 
sion, the debate being continued with great ability and 
earnestness at subsequent meetings. 
The conference was attended by many distinguished 
medical men, some of whom were profoundly influenced 
by the arguments, and none of whom disputed the facts 
brought forward against the theory on that. occasion.” 
“The leader of the debate, and the most prominent speaker, 
was Dr. Bastian, to whom also fell the task of replying 
on all the questions raised.” ‘‘The coexistence of bacte- 
ria and contageous disease was admitted ; but, instead of 
considering these organisms as probably the essence, or 
an inseparable part of the essence, of the contagium, Dr. 
Bastian contended that they were pathological products 
spontaneously generated in the body after it had been ren- 
dered diseased by the real contagium.” 
