History of the Nematode Worms. 335 
clear nuclei in their deeper layers, whilst the cuticle is distinctly 
annulated. The truncated extremity of the head exhibits the 
most singular comportment ; it bears a roundish chitinous disk, 
usually somewhat drawn in, from the middle of which the funnel- 
shaped mouth originates; at a short distance behind the lip- 
like projecting margin of the head there stand some small pa- 
pilliform prominences. The commencement of the genital organs 
measures 0:017 millim. 
From the want of sufficient material, I have been unable as 
yet to trace the conversion of this larval form step by step into 
the sexually mature animal. I have, hitherto, been able to make 
only a single experiment, and this has scarcely done more than 
prove the fact that my worms fall out of their capsules in the 
alimentary canal of the cat, and remain alive for a long time. 
When I examined my experimental animal eight days after it had 
been fed with the flesh of the infected mouse, I found the young 
worms, not indeed in the stomach, but in the cecum and colon. 
They were not numerous, and presented no perceptible change— 
a circumstance that almost leads me to suppose that they were 
not yet sufficiently mature for conversion into the sexual animal. 
Our Ollulanus, however, is by no means the only Strongylide 
worm with a change of hosts. To all appearance there are a 
great number of forms which behave exactly in the same way, 
except that in them the migration of the embryos in the interior 
of the first bearer disappears, and the intermediate host is also 
different. This I suppose to be the case especially with Stron- 
gylus commutatus from the lungs of rabbits and hares, as also 
with S. rufescens, a species hitherto unknown, which I have 
discovered, together with S. filaria, in the lungs of the sheep*, 
and, indeed, because their embryos agree almost completely 
with those of Ollulanus. The only difference existing in them 
consists in the caudal point (projecting over the lateral chi- 
tinous bands) being straight. In both cases + the embryos are 
developed in multitudes together in the finer branches of the 
bronchi and their terminal dilatations, where they cause a more 
or less widely diffused inflammation, with phenomena of hepa- 
* The characters of this species, the name of which is derived from the 
shimmering through of the brown intestine, are as follows :—Head un- 
armed, with three small lips and a short cesophagus. Thin; the female 
almost span-long, the male shorter. The vulva immediately in front of 
the anus; in the uterus only a few ova in segmentation. 'I'l.c caudal hood 
of ee male short, with thick ribs and two long and rather strongly curved 
spicula. 
+ Here also evidently belong the “ Anguillulide”’ of the lungs of the 
hare, observed by Sollmann (Beilage No. 11 of the Coburger Zeitung, 
1865), which, from his statements, must have been very abundant in 
Thuringia during the last two years. 
