INJURED AND INTACT SKIN OF PIRBRIGHT WHITE W 58 GUINEA PIGS ARE TREATED WITH HYDROCHLORIC ACID AND SODIUM HYDROXIDE; THE ANIMALS ARE THEN SLAUGHTERED AND THE SKIN AREAS EXAMINED BIOCHEMICALLY AND HISTOLOGICALLY. MORPHOLOGICAL FINDINGS BASED ON HEMATOXYLIN-EOSIN PREPARATIONS INDICATE NO DIFFERENCE BETWEEN CELLULAR SKIN REACTIONS TO ACIDS AND BASES; LEUKOCYTOSIS IS MORE PRONOUNCED IN CUT AREAS THAN IN INTACT ACID OR BASED-TREATED SKIN. EFFECTS OF CAUSTICS ARE GREATER THAN ACIDS ON INTACT SKIN; IN CUT WOUNDS ACID EFFECTS SUCH AS NECROSIS COVER BROAD BUT SHALLOW AREAS, WHILE CAUSTIC EFFECTS ARE LOCALIZED, SEVERE, AND LONG-LASTING. AFTER MECHANICAL INJURIES, THE ACID AND SODIUM HYDROXIDE INCREASE REACTIVE ENZYME ACTIVITY AT THE EDGE OF THE WOUND MORE THAN THEY AFFECT TISSUE LEUKOCYTOSIS. BIOCHEMICALLY, ON UNINJURED SKIN THE ACID CAUSES A SIGNIFICANT SURPLUS OF HISTAMINE AND A SLIGHT SEROTONIN DEFICIENCY, WHILE THE CAUSTIC SOLUTION PRODUCES ONLY SLIGHT HISTAMINE INCREASES AND A SLIGHT SEROTONIN DEFICIENCY. IN THE CUT WOUND, THE ACID GIVES RISE TO A HISTAMINE DEFICIENCY AFTER 6 HOURS AND A SEROTONIN SURPLUS FOR THE FIRST 6 HOURS; THE CAUSTIC SUBSTANCE CAUSES A SIGNIFICANT BUT SHORT-LIVED RISE IN HISTAMINE AFTER 3 HOURS AND ONLY A SLIGHT INCREASE IN SEROTONIN. CUTS AND APPLICATION OF ACIDS OR CAUSTICS DO NOT AFFECT SEROTONIN OR HISTAMINE LEVELS IN POSTMORTEM EXPERIMENTS, EXCEPT THAT ACID APPLIED DIRECTLY TO AN INJURY SLIGHTLY RAISES THE HISTAMINE LEVEL. IT IS CONCLUDED THAT CELLULAR REACTIONS TO MECHANICAL CUTS ARE CONSIDERABLY STRONGER THAN TO ACID OR CAUSTIC BURNS AND THAT CELLULAR REACTIONS ARE MORE SIGNIFICANT THAN BIOCHEMICAL REACTIONS FOR THE DETERMINATION OF WOUND AGE AFTER CHEMICAL EFFECTS ON SKIN. THE RESULTS ESTABLISH THAT THE MURDER VICTIM IN QUESTION WAS FIRST SPLASHED WITH ACID, THEN SLASHED. NOTES AND ILLUSTRATIONS ARE SUPPLIED. --IN GERMAN. (KMD)