OF MICROSCOPIC OBJECTS. 173 
mouth of the animal, and an incision made directly back- 
wards in the middle line above to some distance behind the 
tentacles; the tongue is then immediately brought into view, 
lying along the floor of the mouth.” 
Dr, Alcock’s method of dissection will be found to differ 
in some degree from the general rules before given; and 
when the tongue is dissected out he washes it for one hour 
(shaking it now and then) in a weak solution of potash. 
After cleaning thoroughly in water, it must be mounted by 
one of the methods before mentioned. 
Mr. Edwards, of New York, no mean authority, gives his 
experience as follows:—I use a rather strong solution of 
caustic potassa, the strength of which I cannot specify as it 
must differ with the species under manipulation, as some 
ribbons (or tongues) are injured much sooner than others. 
Plunge the whole animal in this solution; in the case of 
very small creatures shell and all. I have found it better 
to let the animal stand until it dies and begins to decom- 
pose, when it can readily be removed and falls in pieces. 
The lingual ribbon is not so easily decomposed. Now place 
and leave the animal in the potassa solution for some days, 
or boil at once. Almost everything is now dissolved but 
the shell, some few fragments, and the desired ribbon. 
Wash carefully with fresh water, and if it is to be preserved. 
before mounting, remove to alcohol. ‘To mount it, remove 
from the spirit and boil a short time in turpentine, when it 
can be put up in Canada balsam. Mr. May expresses him- 
self as “standing utterly aghast”? at any man so interfering 
with nature as to put up these objects in balsam, thus 
pressing and destroying their true forms. He recommends 
a cell and a weak form of Goadby’s solution. 
Amongst insects, especially the grasshopper tribe, are 
found many which possess a gizzard, armed with strong 
teeth, somewhat similar to those of the molluscs. It 
requires great nicety of manipulation to obtain these for the 
microscope; but Mr. L. G. Mills, before quoted, gives the 
following instructions :—Kill the insect with chloroform and 
