15
the second to a more circuitous infection, perhaps by a second generation
living free in water.
I will now close these descriptions, by giving a few notes on three peculiar
forms of mature coccidia seen by me and figured in the plates.
Plate I, figures 18 and 19, and the lowest coccidium shown in Plate VIII,
are seen to have a peculiar striated structure. Two of these were found in
mosquitos of the 6th to 7th day, and one (Plate I, figure 19) in a mosquito of
the 12th day. The striations appeared to arise chiefly from one or two defined
particles placed near the foci of the oval parasites, but were also present in
other parts. In Plate I, figure 18, the bright oil-globules were arranged very
regularly round and a little within the circumference, as seen on a plane through
the centre of the cell.
Plate I, figure 20, represents the shrivelled capsule of a burst coccidium in
a mosquito of the 12th day. It contains ten or eleven black sausage-shaped
bodies. Similar bodies were seen in another collapsed capsule in the same
mosquito ; arad also in a broken capsule in a mosquito of the 7th day.
Plate I, figures 21 and 22, represent two coccidia found in a mosquito of
the seventh day which had lain dead in water for some hours previous to dis-
section. The surface of both just under the capsule contained numerous small
elongated bodies, as figured. In figure 21 they were regularly placed with the
long axis pointing outward, but in figure 22 they appeared to be turned in
different ways and interspersed between superficial vacuoles. The inner part of
each coccidium was hyaline and contained two or three large oil-globules as
figured. It should be remarked that the stomach tissues were decomposing
and full of bacteria not unlike these small bodies in the coccidia.
I refrain from comment on these forms, Other peculiarities in some of the
coccidia were noted, but need not be described here.
3. Staining.—My experiments in this line are as yet very imperfect, but
a few salient facts have become evident. The coccidia, certainly in their
younger stages, are readily coloured by most stains, nuclear or plasmic, simple
or compound, eosine, méthylène blue, hæmatoxylin (Delafield's or Erlich's
acid solution), saffranin, and others. The stomach is first flattened (for the
smaller coccidia) by the cover glass and the specimen then irrigated by a weak,
watery solution of the stain, which generally colours the coccidia in advance
of the basis. I have generally employed weak formalin (3 to 10 per cent.)
or glycerine with arsenious acid for mounting; neither is very satisfactory.
Whether we use plasmic or unclear stains, the results appear the same
(pending further study). The younger cells consist of an ectoplasm which
colours readily, and an entoplasm which is more or less indifferent to the stain.
The granules take the stain mildly, while the vacuoles seem to be lost sight of
after colouration.
In the coccidia of the second day I have often noticed a peculiar division (?)
of the entoplasm, each chamber of which appears to contain one of the granules,
not in its centre, but at its margin, and seemingly attached to the ectoplasm
(Plate I, figures 6). This arrangement is lost, or multiplied (?), in the older
coccidia, in which the entoplasm looks as if it contains only a mass of colour-
able granules (Plate I, figures 12 and 16), an appearance which is maintained,
so far as I have examined, to a late stage. A large stained coccidium may
easily be burst by pressure, when the stained contents will be forced out
leaving the unstained capsule behind. The hyaline and vacuolated cells of the
third and fourth days present the same appearance after staining (?). Simple
c 2