274 THE AMERICAN MONTHLY [Sept 



special field of the histologist aud microscopist, and it 

 is likely to be exceedingly fruitful in the near future. 

 Comparative pathology is the outcome; this is just be- 

 ginning to be recognized as a part of the medical curric- 

 ulum and is likely to answer many questions along the 

 lines just indicated in this paragraph. — A. M. S. 



The Detection of Blood by Means of the Guaiacum Reaction. 



EDW. SCHAER. 



The importance of a trustworthy means of identifying 

 blood or blood constituents like hemoglobin, methemo- 

 globin and hematin in numerous judicial cases and the 

 value of a combination, on many rather dijBBcult occasions, 

 of the spectroscopic test and of the methods of prepar- 

 ing the characteristic crystals of hemin (as described by 

 Teichmann, Hoppe-Seyler^ Brucke and Preyer), with the 

 "ozone-transferring" action of the coloring matter of 

 blood towards guaiacum, has induced me, for many years 

 to pay special attention to the last-named blood-test. 



While others have mainly recommended to mix the 

 blood solutions — (obtained by extraction of a fresh or old 

 blood-stain with small quantities of water, either alkaline 

 or acidulated with acetic acid) — under suitable conditions 

 first with an alcoholic guaiacum solution and then with 

 transferable oxygen in the form of hydric peroxide or of 

 the analogous compound contained in old and isolated 

 turpentine oil (for instance, the liquid of Hunefeld,v. i ), 

 and to observe the formation of the so-called "guaiacum 

 blue," the method which I have proposed aims at the 

 preparation of an intimate and durable mixture of the 

 coloring matter of blood derived from the blood stain 

 with guaiacum resin. This mixture may be conserved 

 for an indefinite time as a "corpus delicti," and at every 

 moment strikes a very intense blue color by contact with 

 one or another of the liquids containing loosely combined 



