TRANSLATION. 
On the DeveELopMENT of ECHINORHYNCHUS. 
By Prof. Rup. LevcKarr. 
(From the ‘ Gottingen Nachrichten,’ No. 22, October 22nd, 1862.)* 
The Echinorhynchi, or Acanthocephali, constitute a group 
of entozoa with respect to whose development and _life- 
history we are confessedly at present wholly ignorant. 
The observations of Von Siebold and of Dujardin have, it is 
true, shown that the ova of these worms contain an embryo 
wholly unlike its parents; but how, or under what circum- 
stances, this embryo is developed into the perfect animal, in 
the absence of direct experiments, we have been left, up to the 
present time, merely to surmise. Most observers, and in 
particular Van Beneden and G. Wagener, have been dis- 
posed to assign to the Echinorhynchi, a simple metamor- 
phosis hardly, perhaps, more remarkable than that which has 
been shown to take place in some of the Nematoidea. The 
latter helminthologist goes so far even as to believe that the 
organization of the perfect animal may be discerned in the 
embryo. The hook-apparatus at the anterior end of the body 
of the embryo would in this view be comparable to the pro- 
boscis of the perfect worm, and a pair of strap-shaped organs 
in the interior (which exist, it should be said, only in one 
species) have been assumed to represent the so-called 
“* lemnisci.” 
In order to put these views to the test, I resolved, in the 
course of the last summer, to institute a series of experiments 
with the ova of Echinorhynchus Proteus, a species which 
abounds in our river fish, and particularly in those of the 
Perch tribe. 
In the common Gammarus Pulex of our ponds and brooks, 
I had already noticed, on several occasions, Echinorhynchi 
* The interesting paper of which we here give a translation constitutes 
the third of a series of ‘ Experimental Researches in Helminthology’ insti- 
tuted by its distinguished author. 
