IV. RECENT OBSERVATIONS ON YELLOW FEVER ETIOLOGY 
A. Sanarelli's bacillus 
Sanarelh 1 claimed from the examination of twelve cases of yellow fever that he 
had established the etiology of the disease. He claims to have found his B. icter- 
oides seven times, that is to say, in more than half of the cases. An examination 
of his account shews that much contamination with a variety of bacteria was met 
with, in fact, it was only from two cases that pure results were obtained, whilst in 
five cases it was not met with at all. The cases may be summarized shortly : — 
Case i — Autopsy 18 hrs. after death — Variety of bacteria ; no B. icteroides . = o 
2 ,, 2 „ Pure B. icteroides . . . = + 
4 During life (liver and finger blood) — B. icteroides and another species = r 
5 Autopsy 8 hrs. after death — Variety of bacteria, including B. icteroides = ? 
6 „ 3 ,, Very abundant B. co/i ; no B. icteroides . = o 
7 „ o ,, Streptococci ; no B. icteroides . = o 
8 „ 2 „ Staphylococcus and B. icteroides . . = + 
(During life, pure B. icteroides from finger blood, liver, and bile) 
9 „ 8 „ Mostly sterile, small undetermined ba- 
cillus, and one tube of pure B. icteroides = ? 
10 „ 6 „ Variety of bacteria; B. icteroides not found = o 
11 ,, o ,, Staphylococci and a bacillus which was 
identified as B. icteroides; the account 
is hardly satisfactory . . . = ? 
„ 12 ,, 6 ,, Mostly sterile ; a chicken cholera-like 
bacillus, and also a not very clear 
account of a bacillus identical with 
B. icteroides, which soon died out . = ? 
,,13 „ o „ B. co/i and Staphylococci ; no B. icteroides =0 
In total — two positive, five doubtful, and five negative cases, a result which is, 
perhaps, hardly sufficient for establishing the etiology of the disease. Moreover, the 
study of the characters of the bacillus does not impress the reader that the same 
bacillus was always met with ; at any rate, a considerable amount of stress is laid 
upon the appearance of certain colonies upon agar, which alone, without other tests, 
is hardly sufficient as a criterion. 
1. Sanarelli, Annates de I'lnstitut Pasteur, XI, 1887, pp. 433 and 673. 
