THE STREPTOTHRICOSES 577 
lial groups is a necrotic zone about which is a loose 
connective tissue full of mononuclears and a few polynu- 
clears. The centre of the colony is made up of tangled 
mycelial threads and necrotic debris. From uncontami- 
nated necrotizing masses we have obtained cultures three 
times out of very many attempts. 
When ulceration or suppurative softening has taken 
place mixed infection with lower bacterial forms natu- 
rally occurs and the whole picture changes. Pulmonary 
complications, with or without evident ulceration in the 
pharynx, also admit other bacteria. Streptothrical forms 
are often easy to detect in stained smears and in cultures 
but the very extensive bacterial flora soon overgrows 
them and attempts at isolation are fruitless. Under the 
best of conditions their colonial development is slow 
and tiny until they are well accustomed to saprophytic 
life. The complicating bacteria that have been identified 
are Streptococcus pyogenes, pneumococcus, pyocyaneus 
and colon bacilli to which may be added moulds of the 
Aspergillus group but these all have been variable in 
numbers and appearance; the most frequent and there- 
fore probably most important secondary invader is an 
organism we have not been able to identify. 
This germ, a tiny, Gram-negative, non-motile rod with 
a tendency to bipolar staining, will appear in smears 
from an ulcerated necrotic mass, from the nasopharyn- 
geal exudate and from pulmonary lesions and may develop 
upon agar or blood media, for the first generation but 
refuses to grow after that despite our best efforts. At 
present we hope to have it by growing material a long 
time in blood broth. Microscopical examination has not 
revealed it in the tumor-forming variety but on one 
occasion it was found in the lung ; its Gram-negative char- 
acters make its detection in tissue very difficult. For 
obvious reasons the importance of this germ cannot be 
estimated but it seems from the frequency w^th which 
it is encountered that in some manner the streptothrix 
