346 Prof. R. Leuckart on the Developmental 
into little worms, 0°34 millim. in length, which, on the conclu- 
sion of their embryonic development, immediately break through 
the outer capsule of the egg, and move about briskly in the 
mud. Without a knowledge of their parentage, we should refer 
them to the free Anguillulide or, rather, Rhabditide. Like these, 
they possess a simple, narrow and short, chitinous buccal tube, 
which is followed immediately by a long muscular pharynx, the 
posterior bulbous enlargement of which contains three flapping 
chitinous teeth, of conical form. The anterior half of the pha- 
rynx also forms a dilatation, but this possesses a more elongated 
cylindrical form. The body is rather compressed, somewhat 
diminished in front, and drawn out behind into a long and 
slender tail, the tip of which is separated in the form of a distinct 
appendage. 
Moreover not only the structure, especially of the pharyngeal 
section, but also the mode of life, reminds one of the species of 
Rhabditis. The animals feed and grow, and change their skins, 
as if they had to earry on a free existence throughout their 
lives. 
In about a week the little worms have grown to twice their 
original length. Their structure remains essentially the same 
as before (with the exception of the loss of the caudal tip, which 
is thrown off with the first change of skin), being only changed 
in this respect, that the armature of the posterior dilatation of 
the pharynx has been lost, and the muscular strize which were 
previously distinct at this point have made room for some clear 
vesicles. 
At this stage of development the free life of our worms is 
concluded. ‘They indeed remain alive for a long time (some 
even for more than two months) in. mud and water, but they 
undergo no further changes. 
From the analogy of the other parasites, we might have ex- 
pected that the young Dochmi would now immigrate into an in- 
termediate host. But all my experiments made in this direction 
produced no result. Sometimes, certainly, the worms were 
observed in small water-snails (Physa) which lived in the same 
vessel with them; but it appears to me that this immigration 
was merely accidental, not only because the worms remained 
unaltered in the snails, but especially because I have ascertained 
by direct experiment that such a migration is not necessary to 
bring the worms to their perfect development. I have, in fact, 
succeeded in rearing the young worms directly to sexually ma- 
ture Dochmii in the intestine of the dog. 
In a dog which had been experimented on eight days pre- 
viously, the parasites were found nearly unaltered, and, indeed, 
all in the stomach, mostly in the cardiac half. The only re- 
