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Fig. 27.—Microphotograph o£ Human Spermatozoa X 900. (Ret Bahadur K. N. Bagchi)
or their ova which infest the female genitals. A medical jurist is rarely re-
quired to examine a fresh specimen of semen, although he may be called
upon to find out living spermatozoa in the vagina, if a female is brought to
him soon after an alleged rape. A drop of mucus is removed from the vagina
by means of a glass rod, is placed directly on a slide, and is diluted with a
drop of normal saline. It is then covered with a cover glass and examined
under the high power of a microscope, when motile spermatozoa, if present,
will be seen. Dried seminal stains cannot be examined so easily. They re-
quire suitable solvents for bringing out spermatozoa under the microscope.
A solution containing one drop of hydrochloric acid in 44 cc. of water is
considered the most suitable for obtaining the suspensions of spermatozoa
from dried stains on fabrics. A ten per cent solution of glycerin in water
or in normal saline has been suggested as a useful solvent, but it is regarded
as unsuitable for making dry specimens on slides for staining. To suit the
climatic conditions of Upper India, Dr. Hankin,50 late Chemical Examiner to
the Governments of the United and the Central Provinces, elaborated a me-
thod for detecting spermatozoa in seminal stains. The method, consists in
boiling the stained fabric in a tannin solution before dissolving it in a solu-
tion of potassium cyanide so as to render the spermatozoa capable of removal.
The fabric is then placed on a slide, teased with dissecting needles and stained
with carbol fuchsia, when it is examined with a medium power lens. This
method is too long and complicated to be of any use in a laboratory where
a large number of seminal stains are examined every day.
A simpler method, which is equally effective and is largely used, consists
in moistening a small strip of the stained fabric with a few drops of acidu-
lated water in a watch glass for thirty to sixty minutes in the case of fresh
stains and for three to four hours in the case of old stains, and keeping it
covered to prevent drying. During this period the spermatozoa are softened
50. Brit. Med. Jour., 1906, Vol. II, p. 1261.