In the consideration of the first two causes the author advocates using injections of low melting points only at all times; in fact, from his experience with over two thousand subcutaneous injections, he relies entirely upon such paraffins or hydrocarbon mixtures as are semisolid at 70° F., appearing as a white cylindrical thread from the needle of the syringe as pressure is applied.

With such a preparation and a careful introduction of the needle, as described later, and with the injection of an amount much less than that needed to correct the deformity and proper digital compression on the blood vessels and about the site of the injection embolism is practically impossible.

The avoidance in the third instance is self-evident, and it is to the fourth fault and cause that we must pay particular attention.

Stein says that all that is necessary to avoid puncturing a vein is to first introduce the needle alone under the skin and to attach the syringe only when it is found no flow of blood results from the puncture thus made.

Freeman and the author add to this by advocating the use of a somewhat blunt-pointed needle instead of the extremely sharply pointed knife-edged needles usually furnished with syringes intended for this purpose.

11. Primary Diffusion or Extension of Paraffin.—The spreading of paraffin into normal tissues about the site to be corrected by prothetic injection is a fault due principally to a careless use of the syringe. The employments of an improper syringe in which the amount to be injected cannot be graduated or controlled will be considered later—the result with such being hyperinjection. In this event, when the anterior line of the nose is to be restored, the mass is liable to find its way into the loose areolar tissue of the infra-orbital region; in correcting a nasolabial furrow the mass is pushed upward or is forced into the tissue of the cheek above it, aggravating the trouble; in obliterating a frown it travels upward toward the margin of the scalp, giving a median prominence to the forehead that is found to be very difficult to correct; in injections about the mouth the mass moves down upon the chin or accumulates at the angle of the jaw; in correcting the creases beneath the chin it seeks the sides of the neck, even traveling to the superior border of the clavicle at its sternal third. Many other forms of such diffusions can be mentioned directly due to primary diffusion the result of hyperinjection.

Enough has been said of the danger of hyperinjection, yet even with a proper amount of the injected mass this distention may be observed. To avoid this the operator, or his assistant, should compress the margins of the site of the injection with his fingers firmly applied, as, for instance, in the injection of the root of the nose pressure should be made at both inner canthi and over the tissue just above the root of the nose and beneath the finger tips.

Downie advocates the use of celloidin in the correction of a saddle nose as follows: He paints a band of celloidin or collodion down each side of the nose, limited by the line of junction with the cheeks, and another band across the root of the nose. These painted on bands he allows to dry and contract for fifteen minutes before undertaking the injection.

The contraction of these bands prevents to a certain extent the spreading or extension of the liquid paraffin into the cellular tissue about the eyes, yet experienced digital pressure is at all times to be preferred.