280 
Urethral SpirocJiaetosls 
included. On the first day on which the patient was seen, that is on 
the second day after the discharge had started, a hundred spirochaetes 
were measured, and fifty on each succeeding day until the discharge 
ceased. The shortest of these three hundred parasites measured 5p, 
in length, the longest 20/a, and the average was ll/a (see Table I). 
Table I. Measurements of the length of Spirochaeta urethrae Macfie. 
Date 
Number 
measured 
Minimum 
length 
in microns 
Maximum 
length 
in microns 
Average 
July 29 
100 
t) 
19 
11 4 
„ 30 
50 
7 
19 
1118 
„ 31 
50 
7 
18 
10-82 
August 1 
50 
5 
18 
10-12 
9 
>> ^ 
50 
7 
20 
11-50 
300 
5 
20 
11-0 
On distributing these measurements it was found that the commonest 
length of the spirochaete was 10/a, seventeen per cent, having been 
of this size, and that 65 per cent, of the parasites measured from 8/i 
to 12/r. It would be of very little assistance in recognising the spiro¬ 
chaete to know that it measured from 5/r to 20/a in length, especially 
as it is probable that both smaller and larger individuals would have 
been found if a greater number had been measured; but to describe 
it as an organism measuring most commonly 8/a to 12/a and sometimes 
being as short as 5/a or as long as 20/a would be a more serviceable 
definition. This statement is preferable also because it discounts the 
pre-division forms which really should not be taken into consideration 
since they are practically and often visibly double. 
Chart I. 
The distribution according to length of Spirochaeta urethrae Macfie. 
In Chart I, these measurements of length are shown graphically. 
The curve is a striking one, with a well marked crest at 10/a, and shows 
most distinctly that the lengths of the majority of the spirochaetes 
fell within five microns of each other, between 8 /a and 12/a. The 
curve is interesting also because it shows a slight subsidiary crest 
at 14/a. This is due to the inclusion of pre-division forms. These 
double forms, composed of two spirochaetes connected together by 
a fine filament, were frequently seen both in fresh and stained prepara¬ 
tions. There was evidently considerable variation in the size attained 
