ETIOLOGICAL MOMENT IN AMERICAN SWINE PLAGUE. 129 
when the pole ends have an absolutely round, coccoid form. All 
these phenomena can be seen in an uncolored specimen, or in the 
living organisms in a stage of active proliferation in the so-called 
“ hanging drop.” Naturally, they can be still better seen when 
the coloring glass specimen has been colored. With regard to the 
hanging drop cultures, I have found it advisable to add a small 
amount of a freshly filtered aquous solution of coloring material 
to the sterilized boullion of the drop cultivation; the organisms 
take up the color at the pole ends, or refracting points, and be¬ 
come still more distinct. When added properly, the coloring ma¬ 
terial does not seem to affect their vitality. 
Saturated alcoholic solutions of the dyes must not be used for 
this purpose. 
Of all the micro-organisms it has ever been my lot to study, 
either in covering glass specimens, in life, or in tissues, this group 
of bacteria, with clear centers and colored ends, which form the 
sporules, is the most puzzling. One is certainly at a loss, at first, 
where so many cocci come from; this perplexity can never be 
overcome except by studying the developing phenomena of these 
micro-organisms in the hanging drop. 
One sees cocci of various sizes and oval organisms of the gen¬ 
eral dimensions of the larger cocci, groups of three or four ele¬ 
ments attached together, bodies end on, appearing like micrococci, 
and the mature object with its refracting ends and non-refracting 
middle piece, but never rods. 
All these conditions or biological phenomena constitute a 
pure cultivation. 
The method of proliferation is as follows: 
First let me say that this micro-organism is most actively 
mobile in fluid cultivations , and that every one of the (to be des¬ 
cribed) biological phenomena can be seen, and are better seen, in 
a fluid culture than any other way. 
The first biological phenomena to be seen—apparently so, at 
any rate—is the augmentation of the quantity or extent of the 
non-refracting (uncoloring) substance. This portion—the middle 
piece—of the micro-organism becomes longer, but no thinner. 
The refracting poles are thus placed at twice or even three times 
