Medical Officers of the Army of India.
of the disease by microscopical examination of the dung so easy a matter
that an inspection of even the most cursory character usually suffices. The
ova when deposi ted measure . 21/31"—1/250" (about 0. 11mm. ) l ong by 1/480"—1/500"
(about 0.05 mm.) wide, being thus rather narrower in proportion to their length
than those of Dochmius duodenalis, to which, as already remarked, they present
a strong resemblance in all other points. They present too, in perhaps an even
more marked degree, the flattening of their longer sides, and exhibit a more or
less segmented yelk, surmounted by a perfectly clear space, which is wider at
the poles than elsewhere, the shell being as perfectly clear and transparent as
the zone of fluid within it, and exhibiting microscopically a marked double
contour. In freshly deposited dung, the ova will usually be found to be 4—12
segmented, but even earlier stages, and others in which the first indications of
the outline of the embryo can already be made out may occasionally be found;
but under no circumstances do they ever hatch out within the intestine. Doubt-
less, as Leichtenstern has experimentally demonstrated in the case of Dochmius
ova, the cause of the ova not hatching out while still within the intestine is, that
the presence of a free supply of oxygen is essential to the process, and the supply
of this gas within the intestine is very limited. As might be expected from
the general fragility of the envelope of the ova, they hatch out very shortly
after deposition.
Experiments were made with cultivations of diluted dung spread over moist
sand, with the slightly moistened dung set aside in a covered glass, with the
dung suspended in water, and also with dung spread over a patch of garden soil
enclosed within four planks. As far as concerns the hatching out of the eggs, it
seems of little moment which plan he followed, though the experiments gave
some reason for thinking that the more abundant the supply of moisture, the
more rapid was the process, the eggs suspended in water hatching out, on the
whole, more rapidly than those which were kept simply moistened; but, though
the earlier stages of growth proceeded in water at perhaps an accelerated rate,
they soon came to a standstill, and it soon became evident that water could
not be considered a natural habitat for the Rhabdites. These points are illustra-
ted by the following experiment : —
April 26.—Some dung from an affected animal, containing immense numbers of ova,
diluted with water, and spread over a surface of clear sand in a crystallising glass.
April 27.—Ova further advanced in segmentation, but as yet no embryos. A portion
of the surface of the cultivation set aside in a shallow tray of water.
April 28.—In the original cultivation there is but little change to be made out : on the
othen hand, in the material set aside in the tray of water, a few embryos have already
hatched out, and most of the ova contain lively embryos.
April 29.—Ova in original cultivation hatching out. There are now large numbers of
embryos in the tray of water, some of which have grown considerably, and are sufficiently
advanced to admit of the genital area being made out.
April 3o.—The embryos in the original cultivation are now about as advanced as those
C
9