206 THE AMERICAN MONTHLY [September, 



scopical examination of the blood showed that it could not have been 

 that of a man, for the corpuscles were elliptical in shape. A few days 

 later the supposed deceased was captured and arrested in a city about 

 five hundred miles distant from the scene of his disappearance. He con- 

 fessed to having concocted and carried out the plot unaided ; that the 

 blood was spattered about by cutting off the heads of two chickens, 

 which were then tied to a board and dragged through the snow to the 

 river, where they were pushed into the ■ hole previously cut through 

 the ice. 



A witness is sometimes asked to give his opinion as to the probable 

 age of a blood stain. It is generally easy to recognize a fresh specimen, 

 though in stains but a few days old the physical appearance is frequently 

 the same as those of months or years standing. The question of solu- 

 bility has been carefully investigated for the purpose of throwing addi- 

 tional light on the subject. In a stain which has been dried but a few 

 hours the blood corpuscles are more easily restored to their original 

 state than in an old one, but the information thus derived is not always 

 to be depended upon. The most trustworthy information to be obtained 

 on this subject is by ascertaining the chemical changes which have taken 

 place in the coloring matter ; i. e., whether it is in the form of haemo- 

 globin, methemoglobin, or haematin. By this method one may be able 

 to approximate the age of a given stain within certain limits, but the 

 greatest possible caution should be used in expressing an unqualified 

 opinion derived from any source within our present knowledge. 



One of the unfortunate conditions of present scientific literature is 

 the different systems and unreliable standards which have been taken as 

 a basis of measurement. Most of our modern scientists have adopted 

 the decimal or French metric system, though a few still adhere to the 

 English inch. In our country the English system is in common use 

 by the masses. In the field of forensic microscopy it is necessary, there- 

 fore, that all measurements should be taken and expressed in fractions 

 of an inch. Although it is impossible for the average juror, with his 

 peculiar qualifications, to comprehend the fraction j^Vo" °f an inch, yet 

 it sounds familiar, while to express the same measurement in the terms 

 mikron or millimetre would cause confusion and convey no idea of the 

 size thus expressed. 



A centimetre scale, ruled upon a polished metal surface by the United 

 States Bureau of Weights and Measures for this Society, was adopted 

 as its standard of microscopic measurements, after a long series of re- 

 corded investigations, requiring months of careful observation to deter- 

 mine its errors. Thus the Society has rendered available a standard of 

 known value which may be used within certain restrictions by scientists 

 throughout the country for the purpose of ascertaining, by comparison, 

 the deviations of their own micrometers from the true measure. In 

 making corrections of micrometers ruled in the fractions of an inch it 

 is still necessary to compare them with one of the very few standards 

 in this country, and these difficult of access, or to make the necessary 

 mathematical deductions required in a comparison with the standard 

 centimetre referred to. One of the most convenient and accurate meth- 

 ods in recording microscopical observations, necessary not only in legal 

 but in all other cases, is by photo-micrography. Though photographic 

 prints are rarely admitted in evidence, they may sometimes be used ad- 



