hydatid cysts of the liver a pre liminary puncture with the aspirator should always be performed, as it estab Ic.hes the diagnosis and may effect a core. subdiaphraginatic hepatic cysts the ttanspleural incision \\ itil costal re section at one and the same time should be the operation preferred. SC.gotid (1,[111 iVt. Apr. 14, '6S).
Peculiar symptom observed in two eases of hydatid itiell is believed to be of great value in the diagnosis of im pending or actual perforation of the cyst. It is a highly characteristic aromatic odor, resembling that of boiled plums. Eichliorst (Zeits. f. kiln. Med., B. 17, Supplement H. '00).
11CNV physical sign for hydatid cysts consists in the development of a peculiar sound on combined auscultation and per cussion. Rovighi (Policlinico, No. 11, '94).
Resounding sign described by Santini a valuable diagnostic point. Uniform in single cyst, varying when a number present. Fiaschi (Australasian Med. Gaz., Aug. 20, '95).
lu diagnosis between echinococcic cyst of the liver pointing upward and pleurisy \\itli effusion the complete absence of the breath-sounds and the occurrence of pains beneath the shoulder-blade are signifi cant points. In pleurisy the heart is pushed to the left, in hydatid cysts to the left and upward. Sometimes an elas tic resistance may be felt and fluctu ation occasionally occurs. Cardarelli (Morn. Inter. delle Sci. Med., Feb. 29, '96).
The term hydatid is applied to the bladder-worms, which are the larval forms of the Tania echinococcus: the minute tape-worm of the dog family. 'When fully grown the parasite is not more than four millimetres, or one-sixth of an inch, long. It consists of four seg ments, of which the last alone has fully formed sexual organs. It is very com mon in dogs of Iceland and Victoria (Australia); also in the Icelandic settle ments in Manitoba (Canada), the dogs having been brought from Iceland. The ova of the echinococcus are expelled with the excrement and flnd their way into the alimentary canal of man by water and green vegetables; also by direct con tact with infested dog,s, to the hair of ' which ova adhere and may be carried to the mouths of those who touch the dogs. The disease is rare in Canada and the -United States, as well as in European countries, because the dogs are rarely in fested, else, of necessity, hydatids would be of frequent occurrence among all classes, irrespective of habits as to clean liness.
Morbid Anatomy.—The ovum, having entered the human stomach, loses its covering by digestion, setting free the larva, which, by its hooklets, burrows through the intestinal wall. Some of them meet with and enter a branch of the portal vein and are carried to the liver, where they lose their hooklets, and their cystic development begins. The cyst contains a clear non-albuminous fluid inclosed in a capsule of two layers. There is an outer, thick, homogeneous, laminated, elastic membrane which coils upon itself wherever cut and if with drawn displays a tremulous motion. This is the ectocyst of Huxley. 'Within and closely in contact to this lies the endocyst: a delicate, thin, soft, granu lated membrane, forming the vital part of the bladder-worm. Outside the cap sule there is usually a thick investment derived from the tissues of the infested organ. After the cyst has attained con siderable size buds are produced from the inner membrane which gradually develop into cysts having the two walls identical with the parent-cyst. From these daughter-cysts similar buds de velop and from a tertiary series—the granddaughter-cysts, and so on indef- , initely. In time each of these cysts severs its attachment to the parent and becomes independent. From the inner membrane or endocyst of all these cysts buds arise and become transformed into scolices, or echinococcic heads, present ing a circle of hooklets and form sucking disks. Each of these, transferred to the intestine of a dog, may develop into a tape-worm. The exact manner of the development of these buds is in dispute. It is thus apparent that there is a strik ing contrast between thc development of this parasite and of the Tania The ovum of the latter develops into only one larva capable of producing only one tape-worm, while the ovum of the Tcenia echinococcus produces a larva capable of multiplying itself indefinitely, so that from it an innumerable number of tape-worms may result.