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conchologists have given way to naturalists, who have been 
for the most part Biologists in the true sense of the term; 
not being satisfied with the examination of the animals whose 
skeletons were the shells of the older collectors, they have 
studied the greatures alive, and have watched and noted their 
life-history from the egg to the adult stage. The consequence 
has been the discovery of the fact, that the mode of life of 
many of them as regards their food, is shadowed forth in 
the organs used for the procuring and mastication of that 
food. Hence has arisen the plan of classification, or rather, 
to speak more correctly, determination, by studying the 
organs of mastication or jaws and odontophores. The 
importance will then be at once seen of possessing a means 
of readily and accurately preparing these odontophores, so 
that their characters may be preserved and conveniently 
exhibited. The ordinary method pursued, has been to dis- 
sect out these organs by means of knives, scizzors or needles, 
and after washing them, perhaps with the assistance of a 
camel’s-hair pencil, put them up upon microscopic glass slides, 
either dry or in some preservative. Of these preservatives 
two types have been in common use; the first is Canada Bal- 
sam or some similar resin, which almost totally obliterates the 
delicate sculpturings of the horny teeth, whilst the second 
has been the mounting by means of an enclosing cell in some 
watery fluid, either Glycerine, which also makes these objects 
altogether too transparent, or a solution of some antiseptic 
substance like Kreasote or Corrosive Sublimate. 
In the first place, although this rough mode of manipula- 
ting answers tolerably well with the very largest specimens 
of Odontophores, it becomes entirely useless when applied 
to those delicate ones which are by far the commonest, and 
which, at the same time, possess such great beauty of structure 
and configuration. And in the second place, the preservative 
materials commonly made use of, either mask the most im- 
portant characters or are extremely unreliable. Thus the 
use of cells containing liquids are notoriously objectionable 
to microscopists, for they have learned from bitter experience, 
that it is next to impossible to render such cells perfectly 
