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completely and are easily detachable from the fabric. A piece is transferred
to a slide with its stained surface downwards, and is gently dabbed on the
slide with a pair of forceps. It is then teased with needles to disentangle
completely the spermatozoa left in the meshes of the fabric. Two or three
slides may be prepared from this specimen. One of them is covered with a
cover slip and examined for entire spermatozoa under the high power of a
microscope and the other slides are allowed to dry by evaporation at the
room temperature. In cases where seminal stains are not mixed with blood
or pus, spermatozoa with their characteristic refractile heads and long tails
will be seen in fair numbers and sometimes in clusters. If no entire sperma-
tozoa are found, the other slides are carefully dried, fixed by passing slowly
over a flame two or three times and stained in the usual way by means of
methylene blue or methyl green and eosin. Stained with methylene blue or
methyl green for about fifteen to thirty minutes and counterstained with
eosin for about two minutes the posterior half or one-third of the head as-
sumes a deep red or pink colour, while the anterior half or two-thirds of the
head will appear to be unstained or faintly stained with the basic dye. The
tail is also stained pink.

Ganguli51 has devised a modified method of Hankin for staining sper-
matozoa with erythrosine and malachite green. It is the best method for
staining spermatozoa, especially in India, but it has also the disadvantage of
being too lengthy. However, it must be adopted in those cases where seminal
stains are very dirty. By this method the head, especially the posterior
third, is stained dark red and the tail is stained green. It is better to examine
the slide under the l/12th oil-immersion lens, although it is easy to identify
spermatozoa under a dry lens.

A human spermatozoon varies from 50 to 55 microns in length, and con-
sists of a head, neck and tail.52 The head is ovoid and flattened when viewed
in front and pearshaped when viewed in profile. It is about 5 microns in
length or about one-tenth of the total length of the spermatozoon and is about
3.5 microns in its greater diameter or about one-half of the diameter of a red
blood corpuscle. The neck is very short. The tail is the longest part of the
spermatozoon and consists of a long, slender filament which tapers to a point
at its end and has a vibratile ciliary motion which gives the spermatozoon
its motile power. Spermatozoa lose their activity in the mediums of acids,
strong alkalies, metallic salts, alcohol, glycerin and urine or when heated
above 50°C. ; but they retain their characteristic form for a long time if not
disintegrated by decomposition. In properly preserved garments they have
been identified in stains of from five 53 to eighteen 54 years' standing. Sper-
matozoa are easily destroyed in contact with water, but some of them escape
on account of careless washing, when the stained portion of a garment is
not completely soaked in water. It is interesting to note that spermatozoa
can withstand the action of concentrated sulphuric acid but cannot resist
the action of the bacteria which produce decomposition. Their disintegration
may be complete in less than twenty-four hours at temperatures obtaining
in India, especially during the rainy season if the stains are kept damp. Hence
it is necessary to dry the clothes suspected to bear seminal stains at air
temperature, before they are wrapped up and sent for medical examination.

51.    Ind. Med. Gaz., July 1936, p. 400.

52.   Greval, Ghoshal and Das describe a spermatozoon as consisting of a head, a body
(also connecting piece, middle piece or middle part) and a tail—In abnormal cases there
may be two tails linked to one body or a bifid tail (vide Ind. Jour. Med. Res., XXXVTH,
1, 1950, p. 83).

53.   In his annual report for the year 1924, the Chemical Examiner, ZLP., mentions
that some dried films of semen on glass slides, which were kept in his laboratory un-
treated  and unstained for five years, showed the spermatozoa  in  good  condition and
quite intact.   Scrapings from these failed to respond to Florence test.

54.   Witthaus and Becker, Med. Juris. Forens. Med. and Toxic., Ed. H, Vol. HI, p. 859.