210 ANNUAL KECORD OF SCIENCE AND INDUSTRY. 

 SPECTROSCOPIC EXAMINATION OF BLOOD-STAINS. 



The following process for procuring a strong solution of 

 hgemoglobin for the microscopic test of blood-stains is recom- 

 mended by Dr. Richardson. Procure a glass slide with a 

 circular excavation, and moisten the edsres of the cavity 

 with diluted glycerine. On a clean glass cover, a little larger 

 than the cavity, deposit a very minute drop of glycerine, and 

 in this put the tiniest fragment of a fresh-dried blood-clot; 

 invert the slide upon the thin glass cover, and the glycerined 

 edges of the cavity of the former will adhere to the margin 

 of the latter, and the whole can then be put under the micro- 

 scope. If only a suspected blood -spot, then two or three 

 minute particles of the reddish substance are placed in a 

 minute drop of a three fourths per cent, salt solution, using 

 for this purpose tartrate of ammonium and protosulphate of 

 iron. 3Ionthly Microscopical Journal, January^ 1876. 



MICROSCOPIC DETERMINATION OF BLOOD-STAINS. 



The examination of supposed blood-stains, and the assertion 

 that human blood-corpuscles can be clearly distinguished from 

 those of the dog and guinea-pig, has stimulated observers in 

 devising means for more readily and accurately measuring the 

 corpuscles, and preserving them, as it Avere, for future study 

 and remeasurement. Professor Gulliver, whose measurements 

 of blood -corpuscles are those most frequently cited, has 

 stated, in a communication on the "Sizes and Shapes of the 

 Red Corpuscles of the Blood of Vertebrates," etc., in the Pro- 

 ceedings of the Zoological Society of London, June 15, 1875, 

 that the magnitude of the corpuscles in a single species is 

 liable to certain variations, and that in the same field of 

 vision differences may be observed amounting to at least one 

 third larger and smaller than the average. To lessen, as far 

 as possible, the expenditure of time, and to furnish a means of 

 making comparative measurements more accurately. Dr. J. J. 

 Woodward has proposed to photograph the blood-corpuscles 

 placed on the stage micrometer, both blood and micrometer 

 appearing sharply defined in the picture. The measurements 

 are to be made on the negative. He spreads the fresh blood 

 on the micrometer, after Dr. C. Johnston's method, by means 

 of the edge of a glass slide, and the photograph is made by 



