112 
ME. EAINET ON THE STEHCTHEE AND DETEEOTArENT OF THE 
these cysts lose their fluid hy exposure, they can be redistended by a fresh application of 
moisture, even after they have been deprived of life, shovring that this property of imbi- 
bition of fluid is obviously due to physical causes. These entozoa vary very much in 
size, according to their various stages of development ; but the relative dimensions of the 
white opaque portion and the transparent sac differ most in those individuals which 
may be considered to have attained the adult state. Wherever they occur they are con- 
tained in sacs formed by the condensation of the surrormding tissues, whose strength 
and completeness vary in proportion to the closeness of the muscular fibres between 
which the cysts are found ; hence in the substance of the muscular walls of the ventiicles 
of the heart, these adventitious sacs are strong and well-defined, whilst they are thin and 
sometimes indistinct where the muscular fibres are less closely connected together, or 
when the Cysticerci are situated between a muscle and its fascia ; however, in all situa- 
tions they can be easily distinguished by the microscope from the true cyst of the 
animalcule, their structure being very dissimilar. 
If the adult Cysticercus be subjected to slight pressure, the opaque globular-looking 
portion, which was so coiled up within the oval cyst as to form a spiral of about a tmn 
and a half, will be made to protrude, and then the animal ’^dll present a form which 
will admit of an anatomical division into two parts ; namely, a ventral portion and a 
neck, which is the usual mode of dividing this entozoon. See Plate X. fig. 1. 
The ventral part is in the form of an oval cyst, about half an inch in its long dia- 
meter. It is composed of an extremely thin membrane, rendered uneven on its 
external surface by minute rounded projections, and its internal presents a granular 
appearance, as if covered with coarsely-pounded glass. It is fui’iiished with no -visible 
external opening, and is of the same structure everywhere, excepting where it is connected 
with the neck. Its cavity contains fluid in which there is amorphous granular matter, 
and some highly refractive particles ha-ving an oily aspect, also occasionally minute 
earthy particles which effervesce in acid. 
No fibres of any kind can be distinguished in this membrane, either in its natmal state 
or when acted upon by acetic acid. As this part of the CysbicercuB is formed first, and 
exists as a perfect membranous sac some time prior to the addition and development of 
the neck, there can be but little doubt, this is the part in the perfect animalcule in which 
the function of nutrition is chiefly performed, and therefore that it is entitled, as well in 
a physiological as in an anatomical sense, to the appellation of ventral portion. 
The neck is a tubular projection from the middle of the ventral portion ; its form is 
somewhat pyramidal, and at its free extremity it presents a quadiilateral enlargement, 
whose terminal surface is occupied by four circular discs and a rmg of booklets. See 
Plate X. fig. I h and fig. 2. 
Its length varies very much in different Cysticerci according to thefr age, this part 
continuing to increase in size after the other parts have acqufred certain fixed dimensions. 
The membranous parietes of the neck are of considerable strength and thickness, and 
present two orders of fibres, namely, a longitudinal or supeificial set, and a transverse or 
