ANNULATA. 227 
8vo. Tab. I. fig. 2; according to KNowz it is this species especially which 
is used in Vienna and brought there from Hungary}. 
Hirudo medicinalis is the most useful species of Leech (sangsue, leech, 
Blutegel), which almost everywhere in Europe lives in fresh water, especially 
in ponds, marshes and canals, and in winter, rolled up annularly, conceals 
itself in the mud. This animal lives on the blood of animals (vertebrate and 
invertebrate) exclusively ; the jaws serve to wound and to penetrate the skin. 
The first segment of the body, which also is occasionally parted by a trans- 
verse stripe, has asemilunar form and is not closed beneath. It can extend 
itself as an upper lip for feeling or bend itself downwards to cover the 
mouth. The ten black eye-spots are arranged in form of a horse-shoe on 
the back-side of the head ; the first on ‘the first segment, the two next on 
the third, and the two last on the sixth ring of the body. The organs of 
propagation of the leech are by different writers determined very differently, 
whilst, however, the latest investigations (especially of H. MEcKEL, 
MueEtier’s Archiv. 1844, s. 476—480) bring us back to the generally 
received opinion of former times. According to it, nine pairs of round 
vesicles of a white colour are testes, (TREVIRANUS thought they must be 
held to be ovaries, Zedtschr. fiir Physiol. tv. 2, 1832, s.159—167). By 
means of short transverse tubules these vesicles are connected with a com- 
mon canal which runs at each side of the body; this canal goes forward 
into a structure which is white and consists of many convolutions (the 
epididymis or the seminal vesicle). From each of these two seminal 
vesicles arises a short vessel (vas ejaculatorium), which runs to the spherically 
widened sheath of the penis: the penis can be everted outwards through 
an opening in the twenty-fourth ring of the body. In the fifth ring 
behind this is seen the second sexual opening, that of the female parts ; it 
leads to a wide vagina (uterus, according to Bosanus) which, by means of 
a tube that divides forwards into two branches, is connected with two 
small ovaries or vesicles filled with granular bodies. These two ovaries lie 
between the seminal vesicles and the vagina. The impregnation in Leeches 
is mutual. The Leech lays eggs, or rather capsules, in which eggs 
are contained, 5—16 in number. These capsules or cocoons are three- 
fourths of an inch long, oval and surrounded with a spongy or frothy 
substance, and filled with a brown albuminous fluid. The germs appear as 
round discs; these minute yelks grow by means of the surrounding 
albumen, which is absorbed by a structure which closely resembles a funnel- 
shaped cesophagus, and is already visible on the germ when only half a line 
in size (E. H. Weper in Mecket’s Archiv. 1828, s. 366—418, MUELLER’S 
Archiv. 1846, s. 428—434). 
Comp. on the Leech amongst others : JOHNSON, Treatise on the Medicinal 
Leech, London, 1816, 8vo, and by the same, Further Observat. on the Med. 
Leech. With engravings. London, 1825, 8vo; KuntzMann, Anatomische 
Physiol. Untersuchungen tiber den Blutegel, m. 5 Kupfert.; Bosanus in 
1 Other species still, which have been discovered, may be used for drawing blood, 
as the large black species spotted with white which was discovered in Sweden some 
years ago by WAHLBERG, and named Hirudo albopunctata. 
15—2 
