THE BLOOD-SUCKING LEECHES.
1353
T| * Res
Rig. 244.
I’iratory System consists of small apertures (called stigmata or spiraculee)arranged in two rows on the abdominal surliice, andoccurring at every fifth ring. They lead into littlecavities lined by mucous membrane, and which havebeen called air sacs, pulmonary vesicles, mucous bags,cryptee, or lateral vesicles, containing usually awhitish fluid. They are placed on each side of thealimentary canal, in the spaces between the caecalsacs of the stomach, and are usually regarded as or-gans of respiration. Brandt, however, asserts thatthe respiratory function is effected solely by the skin,and that these vesicles are, in fact, receptacles formucus secreted by a neighbouring glandular appa-ratus, which has a whitish appearance, and in formrepresents a folded intestine. This notion, however,is not new, but was held by De Blainville andJohnson.
The Nervous System consists of two parts:one (which we may compare to the cerebrospinalaxis of the vertebrata) consists of a chain of gan-glia (usually about twenty-three in number) occu-pyingthe mesial line of the abdomen, and connectedby a double nervous cord ; the first ganglion (brain)is placed on the oesophagus, and supplies the eyesand neighbouring muscles. The second part of thenervous system is that lately discovered by Brandt,and may be regarded as a kind of sympathetic sys-tem. It consists of three ganglia (connected to thebrain by filaments, and supplying the jaws), and asingle nerve connected to them, and running alongthe abdominal surface of the stomach in the mesialline.
Of the External Senses three only have beenrecognized : feeling, which resides in the externalsurface of the body ; taste, apparently indicated bythe fondness of leeches for certain fluids (as blood,milk, &c.); and vision, effected by ten eyes (in theform of black spots) arranged in a crescent form atthe anterior or cephalic extremity of the animal.
The Sexual System is double,—that is, eachanimal is androgynous, or possesses both male andfemale organs. There is, however, no power ofself-
(the contact of two individuals being requisite, eac i vera l - rs
t V"*e capacity of male and female). The MALE ORGANS cons• ^ an( j a
8 lc les, two vasa deferentia, two vesicuhe seminales, two ejacu 9 .p|’ e penis
^rounded at its base by what some have termed a prostate
s from the abdominal surface at about one-third distant fromTl~ ^
h^nation<lf
P*ni s two vasa deferentia , two vesiculce seminales, two ejaculatory ducts, and a
^b)ii» ft , Ul !r (,UIl ded at its base bv what Qnmp Visiro t0i*YYio/1 q 1 1 1 be neni.
laity s frc
’'Hite i„? ^ ie FEMALE ORGANS consist of two ovaries, two oviducts (which subsequentlyeJt ^rnall° one )> a bollow organ (uterus) which opens by a contracted aperture ( vagina )That r ’ at a bout the twenty-ninth ring, or five rings below the penis. .
?*bl e eeches are essentially oviparous admits of no doubt; and we have now an »™i-*t at)n P „ C ° Unt °f their development by Professor Weber (Meckel’s Archiv for 1828, p. o ).^qiien rs that soon after copulation an unusual activity pervades the ovaries, in con-a 1d p a ® °f which some ova (termed by Weber germs, by Carus yelks) are separa e ,' leCe 8sa- a ‘ on Sr the oviduct to the uterus, where they stop, in order to obtain the ma ersNth - T for their development, and their proper coats. They here become inves et| ) ar ° us Jike membrane, on the inner side of which is produced (either imi
«
Uterine cavity or from the me ™ b 1 ane itSelf) a a whfch U is'reg U a S rded ast kind of‘"..part for the nourishment of the ova, and whi ou ^ s jj e 0 f the serous
""at. Subsequently a glutinous fluid is deposite flu y ; ves a coating to
’J^enthe ova are expelled from the uterus, part t seems now distended
V, t h’*hi! e part is expelled' before and after them B'.'V ien white of egg, probably^/vesicles, and has the frothy appearance of well-beaten white bb- L*** the violent contraction of the uterus.