368 
The Lung Parasites of Cattle and Sheef, 
— Emhrijo 
Strongyle 
alive in 
for Jive 
months. Lemjtli 
■gV '^f '^^ inch. 
of 
kept 
Soil 
and sheep's worms, respectively, I may add that when, on the 
25th of March, 1876, 1 again examined some of the earth in 
which the embryos had been kept, the young worms were still 
living (Fig. 5). They had lived under these artificial condi- 
tions in a closed earthenware vessel, all through 
the winter. During the five months that had 
elapsed, the soil was kept moist, but the vessel 
was placed near the window, where the tem- 
perature was often below freezing-point. Still, 
the only change of structure noticed consisted 
in the formation of a mouth and short oesopha- 
geal tube, represented by a narrow chitin-line. 
Earth-icorms ingesting Embryos. — When, on 
the 25th of October, 1875, I was making a 
microscopic examination of the surface of the 
sifted soil that had been placed in a watch- 
glass (and subsequently deposited under a bell- 
jar, enclosing ferns), it happened that a sudden 
upheaval of the soil declared the presence ot 
an intruder. This was a small earth-worm, 
barely an inch in length, 
accidental ; but we may 
wandered from the dry 
seeking a moister and, 
genial soil. Be that as 
Hi 
Its introduction was 
suppose that it had 
fern-pan, 
soil of the 
therefore, more con- 
it may, I determined 
to ascertain if the earth-worm had swallowed 
any of my experimental embryos. Accord- 
ingly, after washing the worm under a water 
tap, 1 snipped off the lower end of its body. 
The contents of the divided intestine of the 
worm were then allowed to escape on a glass 
slide, for examination with the microscope. 
This done, I had the satisfaction of finding 
strongyle ova and embryos in the earth-worm's 
faeces. Some of the freed embryos were ktrger 
than others. Not unnaturally, this interesting 
find suggested a possibility that, in the ordi- 
nary course of nature, earth-worms might be 
called upon to play the rule of intermediary 
hosts to the strongyles of the calf, and perhaps also to the lung- 
worms of the sheep. On this hypothesis (which had not been 
previously framed by helminthologists), I resolved to continue 
the investigation ; and, as a first step in the process, the unequal 
halves of the divided worm were replaced in soil — this time in 
ordinary earth that had not been sifted through fine muslin. 
Characters of the ingested Parasites. — The more advanced 
