INTESTINAL WORMS. 173 
larvee, Cercarie, from the larval state to be changed into pupe, and 
from this finally to become Distomes?. 
Besides these changes of Distomes, of which the entire series, in 
its chief features at least, has been investigated, there are others 
relating to Zanie which [until lately] were only observed frag- 
mentarily. Such was that of LEBLOND, who found in the peritoneum 
of Murena conger a worm enclosed in a cyst and containing a 
young Tetrarhynchus. He described this larva of Tetrarhynchus as a 
species of Amphistoma and the Tetrarhynchus as its parasite”. M1Es- 
CHER also made similar observations. Sometimes the successions of 
development appear to be possible only on change of abode. The 
simple Ligule of fishes are found, according to RUDOLPHI, in birds 
that feed on fishes in their more perfect form and furnished with 
developed sexual organs: the worms of the [supposed] genus 
Scolex, that live in Plewronecte, are probably changed in the bodies 
of Rays and Sharks into Bothriocephali, and the Bothriocephalus 
solidus, that lives in Gasterosteus pungitius, is changed, according to 
ABILDGARD® and CREPLIN, into the Bothriocephalus nodosus of water- 
birds (Mergus, Colymbus, &c.), which feed on that fish. That worms 
should thus continue to live in other animals becomes less surprising 
when we consider their tenaciousness of life; Ligule have been 
found alive in under-cooked fish; Rupoupur found individuals of 
Ascaris speculigera stiff and hard in the gullet and stomach of a 
Cormorant that had been kept for eleven days in spirit of wine 
which returned to life in warm water: and Miram saw individuals 
of Ascaris acus from the Pike dry and sticking to a board revived 
by water, and in some instances moving a part which had imbibed 
the fluid whilst the rest continued shrivelled up and adhering im- 
moveably to the board*. 
These observations prove, by the way, that it is not necessary 
to have recourse to equivocal generation in all cases of Entozoa 
where their existence appears to be inexplicable by the ordinary 
mode of propagation. 
[Tape-worms attain their full development and mature sexual 
1 See STEENSTRUP Alternation of Generation. 
2 Ann, des Se. nat. sec. Série. Tom. vr. Zool. pp. 289—295, pl. 16, f. 1—5. 
3 Rupouput Lntozoor. Hist. Nat. 11. P. 1. pp. 60, 61. 
4 Winemann’s Archiv f. Naturgesch. 1840, 1. 8. 35—37. 
