64 American Quarterly Microscopical Journal. 



and with certain objects such as the Orbiculina and Orbitolites, 

 or Peneropolis from Bermuda sand, there is no method equal to 

 it. 



The afternoon session was given up to the exhibition of 

 instruments and apparatus. 



The subject discussed on Thursday was principally angular 

 aperture. Mr. W. H. Bulloch, of Chicago, made some pointed 

 remarks upon the 



"formulae of objectives." 



He had some carefully-made drawings, showing the exact 

 course of the rays through several objectives which have oc- 

 casioned some discussion in the English journals. 



Dr. Geo. E. Blackham followed with a long, but interesting 

 paper on 



** ANGULAR APERTURE," 



which, owing to the nature of the subject, is too lengthy for 

 our columns. 



Mr. C. M. Vorce took up the remaining time in the forenoon 

 with a paper on 



"mechanical FINGERS." 



In the afternoon Mr. R. Hitchcock read a paper on 



** ANGULAR APERTURE DEFINED," 



an abstract of which appears in another place. 



After the reading of this paper, Dr. R. H. Ward gave an 

 account of his study of the ashes of leaves. This subject has 

 already attracted considerable attention, and we may expect 

 to hear more from it. Dr. Ward considers it to be of no little 

 importance in vegetable histology. 



Rev. A. B. Hervey then spoke for a few minutes about the 



"classification OF ALGAE." 



Our next number will contain a more complete paper on 

 this subject. 



As all the papers of the day were read, debate was in order. 



Mr. Hitchcock then introduced the following resolutions : 



Whereas, the subject of the angular aperture of objectives has been 

 discussed for many years without great benefit to science, or showing 

 even now a fair prospect of satisfactory solution; 



Whereas, we believe that much of this discussion has sprung from 

 the undefined meaning of the term ; and 



Whereas, we, representing in this National Microscopical Congress 

 the various societies and classes of microscopists in the United States, 



