1388 TRANSACTIONS OF THE LINNEAN SOCIETY. 
IV. The fourth paper in this rich part of the ‘ Linnean 
Transactions’ is by Mr. H. C. Bastian, ‘On the Structure 
and Nature of the Dracunculus or Guinea-worm.”’ 
Notwithstanding the numerous attempts that have been 
made to clear up the minute structure of the Guinea-worm, 
some of the main points still remained in considerable obscu- 
rity. Mr. Bastian, in the paper before us, goes far to remove 
this, and has added greatly to the knowledge we previously 
possessed respecting the conformation and probable nature 
of this the most important of human parasites. 
After a brief description of the well-known external cha- 
racters, we have an account of the minute structure of the in- 
teguments, in which the author differs a good deal from pre- 
vious writers on the integument of annelid animals. 
In the Guinea-worm, he says, the integuments are com- 
posed of a transparent, almost structureless chitinous sub- 
stance, arranged in a number of concentric lamelle, presenting 
peculiar linear markings. He denies the existence of any- 
thing like a corium, though, with something like a contradic- 
tion in terms, he regards the integument as ‘‘ composed of 
successive excreted epidermic layers.” If there is no dermis, 
how can there be an epidermis? His further description of 
the structure of the integument in the Guinea-worm and 
some other Nematoidea, as Ascaris lumbricoides and A. 
mystax, is too long for extract, but is well worthy of attention. 
With respect to the muscular system little is added to our | 
previous knowledge, and what is said respecting the nervous 
system leaves it much where it was. The “ water vascular 
system,” he conceives, is represented by four equidistant, 
iongitudinal vessels, which extend throughout the whole 
length of the body, situated, like the [supposed] nervous 
cords, in the midst of a pulpy substance beneath the peri- 
toneal membrane. These canals, he thinks, have been mis- 
taken by previous observers for nervous cords. 
The mature Guinea-worm, as is well known, is crammed 
full of embryos in all stages of development, and it has thence 
by some been regarded as a sexual kind of “nurse.” It 
was also known, from the observations of Leblond and 
others, that the worm contained a slender intestinal tube, 
terminating according to some, in an anus, but accord- 
ing to others, with whom we fully agree, without any 
such outlet. Mr. Bastian has, for the first time, shown the 
true relations which subsist betweeen the embryogenous part 
of the body and this intestine. 
To all appearance the worm represents a simple tube filled 
with young, but Mr. Bastian has shown very satisfactorily 
