206 BACTERIOLOGICAL DIAGNOSIS. 
method by which the so-called polar bodies are stained 
with methylene blue, while the rest of the organism is 
coloured a faint yellowish-brown with Bismarck brown. 
Cultures should be made on blood-serum and should 
not be less than nine nor more than twenty-four hours 
old. Films are spread in the ordinary way and stained 
for half a minute in 
Methylene blue . : I gramme. 
Alcohol (96%)  . 4. “ZO: 
Glacial acetic acid . 50C.Cc. 
Water : , + 950 C.c. 
They are then washed and treated for half a minute 
with 
Bismarck brown. : 5 grammes. 
Water : ; . 1000 C.c, 
The polar bodies are small spheres which are con- 
tained in the bacilli, there being usually two in each 
bacillus, one at each end. In a film specimen of the 
true diphtheria bacillus stained in this way they appear 
as very minute dark blue or black dots, which may 
easily be mistaken for cocci; the bodies of the bacilli 
are often almost invisible. According to some authori- 
ties the presence of these granules in young cultures 
of bacilli which present the morphological characters 
of the diphtheria bacillus, is proof of their virulence, 
whilst their absence proves the cultures to be of the 
non-virulent ‘‘pseudo-diphtheria” bacillus. The method 
can also be applied to films made directly from the 
swabs, and recent researches seem to prove that the 
results thus obtained are of considerable diagnostic 
value. 
If this method be adopted the films must be very 
