The microscopical examination of blood-stains, for the purpose of identifying the presence of the red blood corpuscles, is especially applicable to recent stains. In these the corpuscles may retain, to a great extent, their normal characters; but their condition varies with the age of the stain; they become altered in appearance and irregular in shape with increasing age, until a stage is reached when they become completely disintegrated and unrecognisable. Having obtained a solution of a stain by one of the methods recommended, a few drops should be placed upon a clean microscope slide and covered with a No. 1 cover-glass. In a recent stain, where minute coagula are present, one may be placed on a microscope slide and moistened by breathing upon it several times, and then covering it with a No. 1 slip, or a drop of the glycerine solution may be allowed to act upon it on the slide until it be sufficiently moistened, when it should be covered in the same way. The preparation should be examined through the microscope with a good lens (preferably a ¹/₁₂th oil immersion), magnifying 300 to 400 diameters, and if any corpuscles be found, their characters should be carefully observed and noted. All such specimens should be carefully preserved and labelled with a description of the method of preparation, the case to which they belong, the date of preparation, and the signature of the individual who has made and examined them. It is essential that the preparation and examination of the specimen should be made by the same individual. In certain cases the conditions may be sufficiently favourable to allow of the production of stained specimens, which can be mounted so as to retain their original characters permanently. In every case it is advisable to pursue the investigation with this object in view. This process is especially applicable to recent blood-stains, in which, from preliminary examination, the presence of blood corpuscles has been determined; where complete disintegration of the blood corpuscles has taken place it would not be of any value. It may so happen that by means of stained specimens the identity of blood corpuscles may be more easily established, when the result of examination is uncertain in a specimen not so prepared.