The material injected should be thoroughly sterilized by boiling before using. Brœckært suggests combining an antiseptic with the paraffin and has used guiaform, a combination of formic aldehyde and guiacol in a proportion of five to ten per cent; yet this is of little value when we consider how readily these hydrocarbons can be rendered sterile at high temperatures. =4. Necrosis.=—Death of tissue may follow an injection of paraffin when too much pressure has been applied, or when too much has been injected into the tissue, cutting off the blood supply, or when the injection has been made into the skin instead of beneath it. Again, constitutional disease, such as diabetes or Bright’s disease, may superinduce the breaking down of the tissue. Hyperinjection should and can be avoided by the use of the proper instrument with which the required amount is graduated to a nicety. At no time should an injection be crowded into a dense tissue or where the skin is closely adherent, nor carried so far as to create a blanching of the skin. By carefully injecting the mass this danger should be overcome. Dense or bound-down areas of skin should be loosened and freed, as has already been mentioned. If care be exercised and small amounts be injected, in preference to overcoming the defect in one sitting, pressure effects are entirely overcome. The circulation in the skin over the site of injection should be normal immediately after the operation has been performed, determined by observing the reaction in the color of the skin after delicate digital pressure. =5. Sloughing.=—That sloughing of the skin should be occasioned by the high temperature of the paraffin injected is a condition entirely inexcusable. Paraffin of high melting points 58° to 65° C., or the so-called “Hart paraffin” employed by Wolff, liquefying at from 57° to 60° C., are to be used with caution. The author doubts whether the temperature of the paraffin at the time of injection, even in the latter method, is ever beyond 54° C. even if the thermometer registers 60° C. in the liquefying, hot-water bath. By the time it has been drawn into the syringe, which has been heated by dipping into hot water, and the moment it is injected it has lost several degrees in heat. It would not be permissible to inject a molten mass of a temperature so high as to scar or burn the tissues, and the best results of most operators have been obtained with such of the paraffin group that become liquefied at a temperature of not over 45° C. (112° F.).