immature or imperfectly formed joints of the attenuated neck.

The perfectly formed joints demand separate attention. They contain the reproductive organs, part of which are set aside for the development of the ova. The egg-bearing organ forms an elegantly branched structure, which is known to helminthologists as the uterine rosette. In the perfect condition, it probably contains not less than forty-five thousand eggs. These eggs are capable of escaping from the body of the worm by a natural opening, being also dispersed by the rupture or decay of the joint in which they are lodged. Ordinarily, as we have seen, the joints pass out of the 'host' per vias naturales. For a while they enjoy an independent existence, and being able, by alternate contraction and elongation of the body, to travel in any direction, their dispersion brings about the continuance of the species. Not only, however, are they scattered by these natural means, but they are also, passively as it were, transported by sewage distributors and other benevolent persons. Various agencies in earth, air, and water, lend a helping hand.

In consequence of this distribution, swine

experience little difficulty in picking up more or less of the eggs; and as these eggs measure only the of an inch in diameter, it is easy to understand how we ourselves may be liable to swallow them. In short, the wonder is that we escape infection at all, considering that scores might exist in a glass of water without our being able to see any of them by the naked eye. It must be borne in mind that every perfect egg contains a young tapeworm larva. This larva or embryo measures about 12 of an inch in breadth; and in place of a crown of anchorage-hooks, it carries six small weapons arranged in three pairs, one central and two lateral. The central pair are simple stilettos for boring, the lateral being used as tearing and locomotive agencies. At all events, by means of this apparatus, the little creature is able to thrust its way through soft animal tissues. When, therefore, a tapeworm egg is swallowed by a pig and transferred to the stomach, the gastric juice dissolves the egg-shell, and the little embryo is set free. The juvenile parasite immediately thereafter proceeds to bore through the walls of the

stomach, and travels onward until it reaches a convenient resting-place. Usually it selects the intermuscular cellular tissue, but, not being very particular in its choice, it may prefer the

FIG. 5.

substance of the muscles themselves,

or may take up its

abode in the liver,

brain, or other or

Portion of muscle with 'measles' in gans of the body of the animal. The

its substance: a a', the cysts; bb, the tapeworm larvæ.

pig is thus, in common parlance, 'measled.'

Measly pork is probably not so common as formerly; nevertheless it is sufficiently abundant to produce tapeworms, more especially amongst the poorer class, whose meat is not always too carefully inspected before it is purchased. Moreover, it should be borne in mind that a pig might contain many measles, and yet be properly deemed a healthy animal; nay, more, if only a few measles existed, the most careful meat inspector would be almost sure to overlook their presence. As a rule, it may be said that pigs reared in the neighbourhood of thickly populated districts are very likely to

be measly, whilst those reared in country districts are seldom or never so. This explains why so large a part of the community resident in the country escape infection.

Cysticercus (telo) cellulosa; a b c, head, neck, and body of the natural size; de, the crown of hooks and suckers magnified.

The ingestion of measly pork which is not thoroughly cooked gives rise to the formation. of the armed tapeworm in the intestinal canal. The larva being set free from its capsule by the action of the gastric juice, attaches itself to the lining membrane of the bowel. For many weeks, or even months, no indication of the presence of the tapeworm is perceptible, but after the expiration of from twelve to sixteen weeks fragments of the worm may be discovered to have passed per anum. By this

time, at least, the tapeworm reaches its adult condition, and if nothing be done to dislodge it, the worm may remain within the bearer for six, eight, ten, or even twelve years. So far as my observation extends, the worm grows comparatively slowly after five or six years' residence. Its powers for evil appear to become more and more circumscribed, and probably eight or nine years usually brings its natural life-period to a close.

The symptoms to which the presence of tapeworm in the human body may give rise are extremely variable. Sometimes, indeed, the bearer is fortunate enough to be little inconvenienced by his guest; but even in such instances the immunity from injury is rather apparent than real. It is apparent, inasmuch as the parasite gradually, and to the bearer unknowingly, steals away a portion of his health. The trifling feelings of weariness and lassitude are usually set down to other causes, and it is only when these indications are succeeded by restlessness, nervous irritability, and headache, that proper attention is paid to the true source of these symptoms. Rather than let any fellow