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are taking place within the egg during its stay in the mucous membrane of the rat’s
stomach and its passing through the intestine canal; in this way, to be sure, it has
reached a stage of development, which eggs extracted from the uterus have not yet
obtained. The not fully developed eggs thus are not hatched in the intestine of the
cockroach but passed with the excrements without change.
The opening of the ripe egg takes place in the foUowing way:
The thicker part of the shell at the poles actually consists of two layers, When
passed into the intestine of the cockroach these two layers probably influenced by the
secretion (Text fig. 2) begin to diverge, forming a cavity between them. The con-
nection with the rest of the shell is then loosened, the outer lamelle falls off
first, after which the inner one is broken, perhaps influenced by some pressure
from the foetus. In the fig. the two lamellæ at one of the poles are observed
to diverge from each other, at the other pole the outer lamella is gone, the inner one
is broken, the hind part of the young one forcing its way through the hole thus
made. At the same time the inner lamella has loosened itself from the rest of the
egg, remaining only as a sort of collar which will soon fall off. The emptied egg now
appears as a ring, consisting of the middle part of the shell, devoid of the thickened
polar fields. To a cursory view these empty eggs will now be found somewhat similar
to the eggs of Trichocephalus, flattened at the poles, on a more thorough examination,
however, no mistake is possible.
The larva when freed from the egg has the shape of a long comma; presenting
the greatest width in the front part and tapering evenly towards the hind part; the tip
of the tail is rounded. On fresh preparations the larva shows no interior differentiation;
it is covered with a rather thin cuticula, somewhat thicker in front. Its length is
about 250 n, its maximal width 13 [i.
Apparently the period in which the larva may be found in the chylus-intestine of
the cockroach is but of very short duration; even two days after the feeding they are
gone, as well as the eggs and the empty shells. It has not yet been discovered
where the larva goes to, on leaving the chylus-intestine; most probably it will make
its way into the intestinal wall, although it has not been found there on fresh prepar-
ations. A rather long time is passed after the feeding until it can be found in the mus-
culature (about 20 days), for the present it must be unexplained where it resides till then.
After having entered the muscles of the cockroach the larva encysts itself, being
then coiled-up trichina-like. The capsule, however, in the Spiroptera-larva generally
is but little prominent, — as distinct from those known from the trichina. Most
frequently no capsule at all will be observed at first sight; only the larva will be
seen among the muscular fibres, coiled-up in a most graceful and regular spiral. As
a rule the tail is placed in the centre, the head at the outside.
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