2S0 Scientific Proceedings^ Roijal Dublin Sociehj. 



tendency to diffuse, wLicli is eliaracteristic of tlie reaction as produced by 

 blood. Seminal stains yielded a pale blue to the naked eye ; but on teasing 

 the fabric in a drop of normal saline, and testing the resultant fluid under 

 the microscope, the spermatozoa failed to react. 



Ptis strikes a deep blue colour, somewhat slowly. I am not sure to what 

 extent this is due to the leucocytes or to the traces of blood which are generally 

 present. 



Urine I have hitherto tested once only, and that was a normal specimen. 

 It did not yield a blue reaction within tlie specified period. 



Milk I have tested on three occasions, and I find that bluish streaks and 

 areas appear almost at once in the eoagulum produced by the acetic acid 

 present in the reagent. They showed no tendency, however, to diffuse, and 

 never became anything like so blue as those due to blood. Boiling the milk 

 did not seem to make any difference. Dried on filter-paper, and the stain 

 tested by imbibition, milk yields a dirty green tinge quite uuHke that of even 

 very dilute blood-solutions similarly treated. 



Siveat I have not tested as such, but have frequently observed the effect 

 of benzidine on extracts of under-garments and socks tliat had been soaked 

 with perspiration. The reaction was always negative. 



Fcecal matter I have not yet tested ; but, if derived from an ordinary meat 

 diet, it would, owing to ti'aoes of unaltered muscle-haemoglobin, undoubtedly 

 give the reaction. It takes two days on a diet free from meat before the 

 faeces are free from haemoglobin (Schlesinger and Hoist, loc. cit.). 



In addition to these body-fluids I have also tested from time to time most 

 of the substances likely to occur as substrata to blood-stains. Metallic iron 

 en masse, or coarsely divided (iron fllings), does not yield a blue colour, but 

 after a few seconds gives a diffuse bright brown coloration. Rust gives the 

 same result. Such specimens of woollen, linen, and cotton as I have tested 

 do not yield the blue reaction, nor do wood, plaster, stone, or leather. 



These are the substances most likely to be met with in medico-legal 

 practice ; and I cannot say that I have found any one of them to give a 

 reaction which, with reasonable care, technique, and experience, could be 

 mistaken for that of blood. 



I come now to a class of objects which, with benzidine, yield colour 

 reactions of a most intense character, quite similar and indeed exceeding 

 those given by blood — I refer to fresh vegetables and fruits. If on a freshly 

 cut surface of raw potato, white turnip, tomato, or onion, some acetic solution 

 of benzidine be dropped, and after a moment followed by a drop or two of 

 hydrogen peroxide, a most brilliant blue colour is, within a few seconds, 

 developed, beginning in the fibro-vascular bundles. These appear distinctly 



