mB; 6 Johnston: Leprosy 367 
authorities had reported favorably upon Cagayan Sulu Island, 
’ but had overlooked the question of a proper water supply. 
The Philippine Commission appointed a committee to make a 
new survey, and Culion Island was decided upon as a good 
site. It was not until 1906 that lepers were sent to the colony. 
The first colonists numbered 500, and at the present time some 
3,000 persons are living there. 
ETIOLOGY 
Leprosy is caused by an acid-fast bacillus—the so-called 
bacillus of Hansen, or Bacillus lepre—which resembles the 
tubercle bacillus both as to morphology and staining peculiarities. 
It is a slender rod, 2.5 to 3.5 microns in length by 0.3 micron in 
thickness. It is usually straight, but sometimes slightly curved, 
and occasionally clubbed forms are seen. It is nonmotile, and 
is not definitely known to produce spores. I have often seen, 
however, in smears from leprous nodules, small rounded bodies 
0.5 to 2 microns in diameter, which are distinctly acid-fast, and 
have noted that where these exist the typical leprosy bacilli will 
also be found after careful search. Leprosy bacilli are found in 
the tissue cells in the lymph spaces, and while isolated organisms 
are frequently noted, a characteristic grouping of from two to 
three to many individuals in a bunch or bundle may occur. This 
has not been inaptly likened to a package of cigars. 
A word as to the differentiation between the bacillus of 
tuberculosis and that of leprosy. The leprosy bacilli are usually 
present in large numbers, often packed in groups, or bundles, 
in the juice squeezed from a leproma or in scrapings from the 
nasal mucosa, provided an ulcer of the septum exists. In 
tubercular skin lesions it is the exception to find a single bacillus 
in juice obtained after such a procedure. The leprosy bacilli 
are said to be less acid-resisting than the tubercle bacillus. This 
fact is in a measure true, but I have often found typical leprosy 
bacilli that were as acid-fast as the tubercle bacillus. 
It has been stated by several authors that the leprosy bacillus 
stains more solidly and when granules are present they are 
coarser and more widely separated than the fine granulations 
of the tubercle bacillus. The bacilli are chiefly spread by the 
lymphatics, but they may be found in the blood stream in the 
nodular type of the disease. The following procedure should 
be used: Puncture a vein and permit the blood to flow into 10 
per cent acetic acid solution in the proportion of 1 to 10, allow it 
to act from one to two hours at 37°C., and then centrifuge. 
Very beautiful specimens may be secured in this way. 
