Full resolution (JPEG) - On this page / på denna sida - Contributions to the Biology and Morphology of Spiroptera (Gongylonema) Neoplastica n. sp.
<< prev. page << föreg. sida << >> nästa sida >> next page >>
Below is the raw OCR text
from the above scanned image.
Do you see an error? Proofread the page now!
Här nedan syns maskintolkade texten från faksimilbilden ovan.
Ser du något fel? Korrekturläs sidan nu!
This page has never been proofread. / Denna sida har aldrig korrekturlästs.
the biggest one a length of 1215 fi, whereas a larva from a stomach of a rat taken one
day after the feeding measured 1248 ^, having thus evidently been still longer, as in
one day it will hardly be able to grow as long as that in the mucous membrane of
the stomach of the rat. On the whole, it is growing but very slowly during the first
days after the transmission to the alimentary canal of the rat, as will be referred to
later on.
The shape is slender (fig. 32) tapering but slightly towards the front end and keep-
ing its width until the anal region where rather quickly it narrows into a conical tail.
The front end is similar to that of the fully developed worm as far as shape and
appearance is concerned (fig. 26). The tail often terminates in two pointed papillæ-
shaped projections the shape of which is varying much according to the different in-
dividuals. Sometimes three projections will be found of unequal size, while in other
cases it proves very difficult to make out whether two or three are present. A most
peculiar wing-shaped prominence may also be found in some cases, the edge of which
is serrated or fringed.
The pharynx is relatively longer than that of the fully developed worm and the
Chitin-intima is comparatively thicker, a faet which will sometimes recall the Rhab-
ditidæ. As to the shape of the diameter I have not yet been able to make out
whether it is prismatic or not. Oesophagus at this stage of development has about
the same length as the intestine; frequently, however, it is somewhat shorter; during
the following period of development the oesophagus, however, grows more quickly than
the intestine, as the front half of the animal increases considerably in length, being at a
certain point of time longer than the intestine. When later on the hind part of the
worm shows the greatest rate of growth the length of oesophagus comparatively
will decrease by and by. Even in the encysted larva the oesophagus has the shape
of the fully developed worm, the front part being slender, passing with a rather
sudden dilatation into the thicker proximal half. The nerve-ring shows itself very
distinctly and half way from the latter to the limit beetwen the thinner and thicker part
of the oesophagus the porus excretorius is situated (figs. 28 and 32). The genital rudi-
ment appears as a small egg-shaped body far back in the animal, nearly on the spot
where the vulva will be found later on. Even at this stage of development it seems
to consist of a number of cells, or at any rate of a syncytium with several nuclei.
When feeding the rat on cockroaches containing encysted larvæ these will be found
to have entered into the mucous membrane of the stomach already the next day. As
above mentioned they may not only be observed here; not seldom they are found
in the mucous membrane of the oesophagus or of the tongue, so that it may
be supposed that the larvæ already are freed from the capsules while in the
mouth of the rat, owing perhaps to a purely mechanical influence during the chewing.
<< prev. page << föreg. sida << >> nästa sida >> next page >>
