at any later, and for obvious reasons. Whilst the extremity is immovably fixed by hydraulic pressure, the adductor muscles are nightly agitated by reflected spasms, and kept on the stretch. The limb becomes attenuated and exhibits marked disproportion with its fellow, the constitution, rest, appetite, suffer gravely, and reduce the patient in weight and appearance. The effusion may still be of a plastic and organizable character; sero-purulent, or exclusively pus: may be free from, or contaminated with structural detritus, benign or destructive. Its composition will naturally determine the issue of the case. If the effusion be mild, plastic, benign, free from deleterious admixture, its partial absorption and final organization into fibrous structure may take place and thus terminate the malady. Or its quantity may lead to a disruption of the cap. sular ligament, and the escape of the intra-articular effusion into the surroundings of the joint, and there become organised and innocuous. Through similar changes the sero-purulent effusion may pass with the same result. But if the articular contents are of a destructive character, they may, by macerating and corroding the acetabulum pass into the pelvic cavity through the cotyloid notch, or through thə capsular ligament, and will invariably give rise to the formation of abscess, corresponding in locality with the place of perforation. In the moment the perforation is effected a new series of symptoms appears, and with which the third stage of the disease is ushered in. The third stage is distinguished by diametrically opposite symptoms. The contrast of the two stages can best be realized by placing them in juxtaposition, It will be seen that the third stage is characterised by unmistakeable clinical manifestations, and by so peculiar a gait of the patient, as to be recognised at a distance. The shortening, adduction, and inversion of the limb, conjointly with the rotundity of the gluteal space, strongly convey the impression of posterior superior dislocation of the femur. This similarity of the two may have led Rust to presume their identity, and ascribe to the action of the contracted muscles the cause of spontaneous dislocation. The morbid enlargement of the caput femoris, said to exist (at the second stage) lent a plausible argument to this hypothesis. What was more simple and transparent, than that the head of the femur partially expelled from the acetabulum by its disproportionate size, should leave it entirely and follow the undue traction of the muscles. This hypothesis of the renowned German surgeon prevailed among the profession; spontaneous dislocation was henceforth a settled fact, against which but heterodoxy could raise its voice. Buehring, of Berlin, if I do not mistake, was the first who took issue with Rust's theory, and attempted to reduce the acknowledged similarity of symptoms to causes widely different from those propounded. In this effort, he derived material assistance from the advancement of pathological anatomy. The question once opened has received a rational solution. At this present moment there are few well informed surgeons who recognize spontaneous dislocation. Nelaton has informed us of a good method to decide the relative position of the femur to the acetabulum. In drawing a line from the anterior superior spinous process of the ilium, to the tuberosity of the ischium, it passes on its way, from one point to the other, the apex of the large trochanter, in the normal position of the femur. It crosses the trochanter more or less below the apex in dislocation. In applying this test in the third stage of morbus coxarius, you will mostly find the normal relations, or so insignificant difference as to preclude all possibility of dislocation. Irrespective to this clinical fact the morbid condition of these points contradict the assertion of Rust in toto. It might rather be said that the acetabulum becomes dislocated, since we often find it extending up, and backward in which direction the femur fellows, but true dislocations belong to the rarest occurrences. I have searched in this respect the anatomical museums, on this, and the other side of the Atlantic, without having found more than about a dozen specimens, exhibiting the conjoined evidences of hip disease and dislocation. In this statement I am borne out by other enquirers. It follows therefore, that dislocation is but a rare incident in hip disease, indeed much more so, than might be rationally expected, considering the actual state of the joint in many instances. If dislocation is practicable in a healthy articulation, how much more predisposed must the latter be, when the acetabulum is denuded and enlarged, the round ligament totally destroyed, the head of the femur diminished in size, the cotyloid cartilage more or less disintegrated, the capsular ligament broken through &c.; which all tend to facilitate the displacement of the femur. It is thus evident, that the slightest appreciable injury should suffice to bring about a dislocation, but its spontaneity cannot be conceived, and must therefore be denied. On the other hand, it must be borne in mind that the joint being more or less tender, is well taken care of by the patient and protected against incidental injuries. One of these means is the play of all muscles by voluntary effort to keep the joint at rest, and thus dislocations are prevented, which otherwise might seem inevitable. Wherever dislocations take place, there can be no doubt as to their being the result of some injury or other, however trifling. That much I can at least assure, that I never myself have had the opportunity of observing a single case of indisputable dislocation consequent upon morbus coxarius, and I have had my finger in the hip joint too often to be deceived. If you examine a patient so afflicted, with the aid of anæsthetics, extending the affected limb, whilst at the same time exercising counter extension by placing your foot against the pelvis, you will notice a certain amount of mobility of the joint, but the absolute impossibility of abducting it. In searching for the cause, a firm and unyielding contraction of the adductor muscles will be found, over which the anaesthetics seem to have no influence whatsoever. It is thus in the third as in the second stage, the malposition of the limb is produced by a single cause, and the rest of the symptoms follow as physical necessities. Now, for instance, let us presume the femur held in undue position of adduction and flexion, and the patient attempt to walk, he would yield the pelvis as much as possible for the purpose of relieving the tension of the contracted muscles. The first thing he does it to rotate the pelvis in its transverse diameter, thus approximating the anterior superior spinous process of the ilium, to the insertion of the tensor vaginae femoris. This accounts for the enhanced angle of inclination with the horizon. By turning the pelvis on its axis at the lumbar articulations, the patient favors the former object. If the pelvis remained quite horizontal and the extremity of the healthy side rectangular to the former, the affected limb would necessarily cross its fellow, and locomotion would thus be rendered impracticable. Hence the affected side of the pelvis is tilted up in proportion to the adduction of the affected extremity, the healthy member is thrown out, (abducted) and paral lelism is thus achieved. If the pelvis is thus out of position, the spine and shoulders have to adapt themselves to the static changes. In compounding the effects of these changes in the position of pelvis and femur, we can almost to a nicety, ascertain the amount of apparent shortening, without regard to the so called spontaneous dislocation. The longitudinal rotation of the pelvis will raise the extremity as much as an inch, the flexion of the femur upon the pelvis, another inch, and the obliquity of the pelvis from one to three inches. Thus the limb may be shortened in the aggregate, from three to five inches, an amount never to be produced by traumatic dislocation of the femur upon the ilium. Most cases of morbus coxarius terminate with the third stage; but comparatively a few advance to the fourth and last stage of the disease, which is a combination of the symptoms of the third, with those of caries, abscesses, fistulous openings and tracts, in the neighbourhood of the joint, local pain, arising from such sources, and hectic fever. Thus it will be seen that hip disease is characterized more than any other, by a certain immutable regularity and chronological succession of symptoms, which, in themselves, furnish the strongest ground for differential diagnosis. Though the first stage may escape the vigilance of the professional attendant, the second will inevitably decide his appreciation of the growing trouble. The third stage is invariably preceded by the second, and the fourth by the former stages. This, at least, has been my observation in a large number of cases, and I entertain no doubt that it is substantially the same with other accurate observers. The exceptions that may be adduced apertain to cases partly not hip disease at all, partly hip disease of a consecutive nature, and consequently blended with other pathological conditions. Periostitis in the neighbourhood of the hip joint often produces similarities of hip disease of a most striking character. We may find in connection with it all the symptoms enumerated under the third stage of morbus coxarius, but this difference will always be manifest: that the symptoms of the second stage never preceded that condition. If the joint is not secondarily implicated in those cases there will be a freer mobility of the same, and no crepitus; whilst on the other hand, the femur is enlarged and tender. Sometimes we meet with malposition of the femur in consequence of Potts' disease, and periostitis of the spine, which may give rise to an erroneous diagnosis. The history of morbus coxarius and affections of the spine is so differentially marked that the mistake may be easily corrected. Eventually, the application of chloroform will suffice to overcome the muscular retractions of the latter, and prove the hip joint to be intact. We owe to Erichsen's careful investigations, our knowledge of the suppurative affection of the sacro-iliac junction, but the symptoms adduced by that author are so widely different from those of hip disease, that they hardly can be confounded. Eventually the careful examination of the corresponding hip joint must necessarily settle all doubts. Chemical Selections. By E. S. BLACKWELL, Esquire, Montreal. The existence of silicium ethyl, containing one atom of silicium and four molecules of ethyl, and having the functions of a saturated hydrocarbon, pointed to an analogous compound in which silicium should be replaced by carbon, which carbon would therefore be saturated by carbon alone. In the same manner as primary, secondary, and tertiary alcohols contain each of them one carbon atom, the four bonds of which are partly saturated respectively by one, two, and three bonds of other carbon atoms, and as these different alcohols may be referred to hydrocarbons of analogous constitution. So it may be presumed that a quaternary hydrocarbon may exist, in which one carbon atom will be saturated exclusively by other four carbon atoms. In methylchloracetol, resulting from the action of phosphoric pentachloride on acetone, it is most probable that one carbon atom is united with two carbon atoms and two chlorine atoms; if, therefore, the two chlorine atoms be replaced by two hydrocarbon radicals, the quarternary hydrocarbon sought for will be obtained. Zinc-ethyl, heated with methyl chloracetol, gives rise to enormous quantities of gas; probably propylen and ethylen. The greater part of the residue, when freed from excess of zinc-ethyl and further purified, boils between 86° and 90°, and is hydride of heptyl C7 H16, or as it may be called from the mode of its formation, carbod-imethyldiethyl. (Bull. Soc. Cheini Paris, 1867, 65.) Pseudomorphine. (C=6, 0=8). O. HESSE. Pelletier who discovered pseudomorphine, 30 years ago, from the small quantity he obtained, was unable to give precise directions for its preparation, and naturally enough, doubt fell on its identity. Hesse finds that it accompanies morphine in Gregory's method, and may be separated from that body by adding excess of ammonia to the alcoholic solution of both alkaloids; the morphine is precipitated, the other remains in solution. Pseudo-morphine is tasteless, insoluble in water, alcohol, ether |