The scolex or higher larval stage of growth forms the well-known pork measle or _Cysticercus_ (_telæ_) _cellulosæ_ of authors. The smallest measles found by Leuckart measured 1/25″ in length. They were obtained from the brain, liver, and intermuscular substance of a pig fed with proglottides about thirty days previously. Only those specimens, however, occurring in the liver at this early period displayed an outer membrane proper to the worm itself, the others being simply invested with capsules formed out of the connective tissues of the host. Many measle-masses in the same host were much larger, presenting an average diameter of 1/6″. The smallest already displayed a smooth, transparent, homogeneous, outer, cuticular membrane, overlying a double, finely-granular corium, the latter being traversed by a branched system of aquiferous vessels. These vessels proceed from a central spot, which marks the position of the so-called head-cone, or _receptaculum capitis_. It is, in fact, the first well-marked indication of that flask-shaped capsule within which the head, neck, and body of the Cysticercus is formed, and which Goeze long ago very aptly compared to a lantern. As growth proceeds, a central granular mass forms the true foundation of the head, its upper or stalk-like extension becoming the future neck and body. Further changes result in the evolution of the internal water-vascular system, the calcareous corpuscles, the marginal transverse foldings of the body, the four suckers, the rostellum, and, in particular, the double coronet of hooks. All these metamorphoses were minutely followed and described by Leuckart, who found the development of the larva to be completed within the space of ten weeks. As regards the injurious effects of this parasite upon man, it may be said to act prejudicially in three separate ways. I have remarked in my ‘Entozoa,’ that this parasite may cause disease and death both by its action in the larval and adult states. It may likewise injure us by rendering the flesh of swine unwholesome. When one or more sexually-mature tapeworms have developed themselves within the human intestine, they are apt to give rise to a variety of unpleasant symptoms, more or less marked according to the habit or irritability of the patient. According to Davaine (p. 103 of his ‘Traité’) the principal features are “vertigo, noises in the ears, impairment of sight, itching of the nose and anus, salivation, dyspepsia and loss of appetite, colic, pains over the epigastrium and in different parts of the abdomen, palpitation, syncope, the sensation of weight in the abdomen, pains and lassitude in the limbs, and emaciation.” In ordinary cases there is always more or less anxiety and restlessness; but in severe cases the sympathetic symptoms are very strongly marked, showing themselves in hysterical fits, chorea, epilepsy, and epileptiform seizures, attended by more or less alarming convulsions.