704 General Notes. [ October, 
“ Mechanical fingers,” by C. M. Vorce, of Cleveland. In this 
paper the mechanical finger was spoken of as a kind of stage 
forceps adapted to objects too small and fragile for ordinary for- 
ceps, and as an important accessory for the microscope, even as a 
means of study of minute forms and to those who do not wish 
to mount objects. Those forms of finger were described which 
are attached to the objective or to the movable stage, and the 
home manufacture of them recommended as easy and effective. 
Their efficiency is greater in proportion to the greater number of 
movements of the stage and sub-stage. The apparatus should 
be furnished with a variety of points for different kinds of work, 
varying from a fine mouse-whisker to a split point of whalebone 
or quill. 
“ Microscopical study of the ashes of leaves,’ by Dr. R. H. 
Ward, of Troy, describes the method by which leaf ashes 
may be prepared so as to preserve much of the structure of the 
leaf. The books speak of the siliceous residue of the leaves of 
with turpentine, and very carefully mounted in soft balsam. If 
slightly crushed in mounting, or containing a trace of carbon at 
some point, the value of the object is often increased. These 
preparations can be made with great ease and rapidity, and show 
the construction of the parenchyma, veins, epidermis, stomates 
and hairs with great beauty and distinctness. In this way was 
prepared a slide of leaf ashes which was recently sent through 
the circuits of the Postal Club and which excited an unexpected 
amount of interest and correspondence. 
_ “Classification of alge,” by Rev. A. B. Hervey, described the 
_ systematic arrangement of sea weeds by means of their peculiari- 
ties of reproduction, and showed how completely our knowledge 
of the subject is due to the microscope. The writer urged the 
more frequent preparation, for use and for exchange, of series of 
- slides illustrating typical species in groups studied by specialists 
-in natural history —{7Zo be Continued.) 
MicroscoptcaL DIRECTORY. —— The fullest list of American 
—  microscopists yet.published will be found in the “ Naturalists’ 
oe ‘Directory for 1878,” published by S. E. Cassino, Salem, Mass. 
ial, also diatoms of Northern Illinois, for good slides or material 
B. W. Thomas, 132 La Salle street, Chicago, Ill. 
ExcHances.—Lake Michigan diatoms mounted or raw mate- 
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