526 PROGRESS OF VETERINARY SCIENCE AND ART. 
almost in vain to answer certain vexed questions respecting 
the multiplication and growth of Entozoa in general. 
Lecke had observed, in 1780, that the water-bladders in 
the brains of giddy sheep were animals, and Fabricius 
(Harvey’s master) was the first to assert the same respecting 
the Cysticercus of the pig. It was supposed they were the 
products of disease, even after it had been observed as pro- 
bable that the intestinal worms were introduced from without ; 
but the enclosed situations in which the hydatids were found, 
and the absence of organs for propagation, caused them to 
be looked upon as animals of spontaneous or equivocal 
origin, the results of aggregation of matter, vitalized in some 
way similar to man and other living beings when first created. 
It had been observed that some animals put forth buds which 
separate from the main trunk, and develope into other 
beings of the same nature. Professor Bendz has observed 
this budding in a form of Cysticercus. 
From the observations of Ehrenberg, in and since the year 
1830, on the Infusoria, the spontaneous generation was 
rendered very improbable. Eschricht thought he was one of 
the first (in 1838) to pronounce with certainty that all intestinal 
worms, without exception, descended from similarly formed 
animals. It was known as certain that the Filaria medinensis 
which occurs in hot countries entered the bodies of men 
from without. The Cercarias were known to undergo a series 
of developmental changes, and hence the origin of the intes- 
tinal worms was supposed to be complicated. Abildgaard, 
the founder of the Copenhagen Veterinary School, had 
observed that a tapeworm, the Bothriocephalus latus,* which 
occurred in the abdominal cavity of the common stickleback^, 
and in the intestinal canal of certain water-birds, never had 
eggs in the former, but always in the latter situation ; and 
that from there it passed into these animals, he ascertained, 
by direct experiments with ducks, which he fed on ban- 
stickles. The conclusion drawn from this was, that certain 
intestinal worms undergo their complete development by 
passing from one animal into the body of one of another 
species. 
Goetze, in 1782, had perceived the great resemblance 
between the head of the hydatid of the liver of mice and rats 
(the Cysticercus fasciolaris) and of the tapeworm of the cat 
(Taenia crassicollis). It was the observation of this resem- 
* According to Alien Thomson the Bothriocephalus nodosus or Scldsto - 
cephalus dimorphus. 
f The stickleback or bansticle is a small prickly fish, the Gasterosteus 
aculeatum. 
