316 MR. R. OWEN’S DESCRIPTION OF A MICROSCOPIC ENTOZOON 
from one another ; but sometimes a larger and a smaller cyst are seen attached together 
by one of their extremities, and they are occasionally observed slightly overlapping each 
other. If a thin portion of muscle be dried and placed in Canada balsam, between a 
plate of glass and a plate of talc, the cysts become more transparent, and allow of the, 
contained coiled-up worm being more plainly seen. 
Under a lens of the focus of half an inch the worm appears to be inclosed within a 
circumscribed space of a less elongated and more regular elliptical form than the external 
cyst, as if within a smaller cyst contained in the larger, like the yolk of an egg sur- 
rounded by its albumen and shell. The worm does not occupy more than a third part 
of the inner space. A few of these cysts have been seen to contain two distinct worms; 
and Dr. A, Farre, who has paid much attention to the subject, has shown me a drawing 
which he made of one of the cysts containing three distinct worms, all of nearly equal 
size. 
The cysts vary in form as well as size, being more or less elongated, and the opake 
extremities being further extended in some than in others: in a few instances only one 
of the extremities is thus produced. Occasionally the tip of one of the extremities 
is observed to be dilated and transparent, as though a portion of the larger cyst were 
about to be separated by a process of gemmation; and these small attached cysts are 
seen of different sizes, as it were, in different stages of growth. This appearance, 
however, I conceive to be explicable without a reference of a power of independent 
vitality to either of the adherent cysts. 
Besides size and figure, the cysts also differ in structure: in general they are com- 
posed of condensed and compacted Jamelle of cellular tissue, but a few are hardened by 
the deposition of some earthy salts, so as to resist the knife, and to break with a gritty 
sensation under pressure!. 
In order to detach the worm from the cyst, which from the minuteness of the object 
is a matter of some difficulty, I have found it best to select a portion of muscle which 
has been placed for a short time in spirits of wine. After separating the cysts from the 
surrounding fasciculi of muscle, and placing them, moistened with a little water, on a 
slip of glass, I have generally succeeded, on cutting off the end of the cyst, or tearing 
it open with the point of a needle, in ejecting the worm and the surrounding fluid 
in which it floats, by gently pressing on the cyst. 
The little worm is usually disposed in two or two-and-a-half spiral coils: when 
straightened it measures from =',th to ;4;th of an inch in length, and from -+,th to 
=tcth of an inch in diameter: a high magnifying power is consequently required for 
its examination. It is cylindrical and filiform, terminating obtusely at both extremities, 
which are of unequal sizes, tapering towards one end for about a fifth part of its length, 
' This change is probably dependent on the death of the inclosed worm, the traces of which are either very 
obscure, or altogether wanting in these ossified cysts. 

