CYSTICERCUS CELLULOSE. — The ripe ova of the Tcenia solium are occasionally received into the human stomach, either by being accidentally swallowed or forced into the organ from below. The human then becomes the intermediate host of this cestode, which is usually the Sus domesticus. It thence invades various tissues and organs. Pigs are sometimes found swarming with these "measles," and in them there is rarely any consti tutional disturbance except possibly at first. If in man only a few of these "measles" become established, the larva may die, become calcified, and produce no mischief. They are very rare in America. The symptoms produced where a considerable number occur or where the localities invaded are sensi tive are sometimes very serious, and are divided by Osier into: general, cerebro spinal, and ocular. The general symp toms resemble in many instances a peripheral neuritis. When the cerebro spinal tissues are involved, very pro nounced symptoms may result, accord ing as the centres are invaded or the more silent regions are occupied. The ocular symptoms can be more or less readily elucidated by a direct examina tion of the eye.
Echinococcic Disease.—This disorder, both general and local in its manifesta tions, arises from the invasion by the larval forms of the Tcenia echinococcus of the liver, intestinal canal, lungs and pleura?, kidneys, bladder, genitalia, brain, spinal cord, bones, heart, and blood-ves sels, and occasionally other organs.
In America this disease is extremely uncommon and even then occurs only in foreigners with rarest exceptions. It prevails in countries where man lives in intimate association with dogs, as in Aus tralia, Iceland, and some parts of Eu rope.
The Tcenia echinococcus lives in the in testinal canal of the dog. It is 4 milli metres long, and has only four segments, of which the posterior one surpasses in length all the others put together. The hooklets are 30 or 40 in number and have coarse root-processes. Only the cyst-worm is found in man.
The development of the embryo takes place in the stomach or intestine, where the shell of the ovum is digested away; it then burrows through the intestinal wall, arriving at the peritoneal cavity or the muscle; or, falling into the portal circulation, it may be carried to the liver, which, in at least one-half of the cases, is its destination. Again, it may enter the systemic vessels and be carried to various organs and regions of the body.
Upon reaching its destination the six hooklets with which it is originally disappear, and a cyst is formed, presenting two layers: a capsule and an endocyst. These embryonal cysts grow and bud, develop from the parenchy matous layer, and themselves become cysts similar to the first one. Thus, the parent-cyst as it grows may contain a dozen or more daughter-cysts, inside which last again a similar process occurs, and a series of third or granddaughter cysts in time develop. From the lining membrane brood-capsules arise by bud ding; these mature into scoleces, which are found to be heads of the Tcenia echinococcus, presenting four sucking disks and a circle of hooklets. Should a scolex reach the intestines of a dog, it may develop into a similar tape-worm.
An interesting and important differ ence between the natural history of the Tai& solium and the Twnia echinococcus is that the ovum of the former develops into a single larva, whereas that of the latter forms a cyst which amplifies itself enormously and from the lining mem brane of which millions of larval echino cocci are in turn produced.
In man, as a rule, the growth of the echinococcus is, as described, endoge nous, the secondary and tertiary cysts be ing contained within the primary; in animals, however, the development may he exogenous. The primary cyst pene trates between the layers and matures externally. A third form is the multi 'ocular echinococcus, occurring in the liver only where the primary cyst-bud develops and is cut off entirely, becom ing capsulated. These joining together produce a dense mass composed of con nective tissue inclosing spaces in which are found remains of the echinococcic cyst oftentimes sterile: i.e., without heads or larvae. It resembles cancer, and the symptoms are those of tumor. The echinococcus lives a varying time, often times many years. The usual change is death and inspissation of the contents and the transformation into a mass of partially-calcified granular material. They may, however, rupture into a serous sac or external perforation, whereupon the cyst is discharged into a bronchus or the urinary passages or the bile-ducts or blood-vessels. From these effects death may follow very suddenly or recovery may ensue. Suppuration may become estab lished, and large abscesses are sometimes formed, which contain hydatid mem branes.