Microscopists who are interested in the study of histology and pathology
have long felt the necessity for a better method of freezing animal and
vegetable tissue than has been heretofore at their command.
In hardening tissues by chemical agents, the tissues are more or less
distorted by the solutions used, and the process is very slow. Ether and
rhigolene have been employed with some degree of success, but both are
expensive, and they cannot be used in the presence of artificial light,
because of danger of explosion. Another disadvantage is that two persons
are required to attend to the manipulations, one to force the vapor into
the freezing box, while the other uses the section-cutting knife.
The moment the pumping of the ether or rhigolene ceases, the tissue
operated on ceases to be frozen, so ephemeral is the degree of the cold
obtained by these means.
The principal advantages to be obtained by the use of this microtome
are, first, great economy in the method of freezing, and, second,
celerity and certainty of freezing. With an expenditure of twenty-five
cents, the tissues to be operated on can be kept frozen for several
hours at a time.
[Illustration: FREEZING MICROTOME.
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