THE AMERICAN 



MONTHLY 



MICROSCOPICAL JOURNAL 



YoL. Y. 



Washington, D. C, October, 1884. 



No. 10. 



The American Association — Sec- 

 tion Gr, Address of the 

 Tice-President. 



The section of microscopy and his- 

 tology of the American Association, 

 at the meeting in Philadelphia last 

 month, although not large in number 

 of members, was well provided with 

 papers of scientific interest. The 

 number of papers was, indeed, less 

 than were presented before other sec- 

 tions, as it must always be, for obvi- 

 ous reasons. 



There were present at some of the ' 

 meetings the Rev. W. H. Dallinger, ! 

 Mr. James Glaishier, and Mr. I. C. j 

 Thompson, of England. ' 



In the absence of the Vice-Presi- '• 

 dent. Prof. T. G. Wormley, the Rev. j 

 A. B. Hervey was called to preside j 

 at the first meeting, on Thursday, i 

 September 4th, and necessary busi- 

 ness of organization was transacted. 



PROF. WORMLEY's address. 



In the afternoon Prof. Wormley de- 

 livered the Vice-President's address. 

 The address was not written, and we 

 give, from notes taken during its de- 

 livery, the only abstract that has been 

 pviblished. 



The subject was the applications of 

 the microscope in chemical and mi- 

 crometric observations. The micro- 

 scope, he said, frequently enables us 

 to determine in a moment questions 

 which, without its aid, would require 

 hours and days. Thus : If a piece of 

 bright copper be placed in an acid 

 solution containing arsenic and heat- 

 ed, the copper becomes coated with 

 a dark deposit. This is common to 

 several metals ; but if the copper 

 strip be then placed in a small tube 



and heated, the arsenic will be sub- 

 limed, and will condense in the cool 

 part of the tube in minute octahedral 

 ci'ystals, which may be recognized 

 ■with a microscope. If the copper be 

 coated with mercury, opaque micro- 

 scopic globules of that metal will be 

 found in the sublimate. Qtiantities 

 of metals, alkaloids, etc., much 

 smaller than can be detected by 

 chemical tests, can be discovered in 

 this way. Of the two metals men- 

 tioned, ^ 0^0 Q ^ of a grain of either of 

 them can be recognized. As further 

 illustrating the delicacy of microscop- 

 ical tests, the alkaloid atropine may 

 be mentioned. With bromine and 

 bromhydric acid this substance yields 

 peculiar crystals, which are charac- 

 teristic in quantities of ototttt of '^ 

 grain. 



Another important application of 

 the microscope is in the identification- 

 of blood in stains, etc. The results of 

 extended observations by the speaker 

 relative to this subject will soon be 

 published. The question presented 

 to a microscopist when called upon 

 to examine a stain may be in one of 

 three forms, viz : i . Is it or is it not 

 blood ? 3. It is admitted to be blood, 

 but what kind of blood ? 3. It is ad- 

 mitted to be blood, and asserted to be 

 blood of a mammal. 



In the first instance the presence of 

 blood can be recognized by the cor- 

 puscles. Serious mistakes have been 

 made by persons who have been de- 

 ceived by finding spores which they 

 regarded as blood-cells. Three in- 

 stances of this nature have occurred 

 in this country within a few years. 

 Such mistakes are not necessary, as 

 it is always possible to distinguish 



