Bauhaus-Universität Weimar

Titel:
The Cyclopaedia of Anatomy and Physiology, vol. 4: Pla [corr.: Ple] - Wri
Person:
Todd, Robert Bentley
PURL:
https://digitalesammlungen.uni-weimar.de/viewer/image/lit29465/425/
SALIVA. 
415 
apparatus, suppose that the spermatic fluid is 
secreted in the tubes, and passed on to the 
vesicle, where it is projected into the cloaca, 
and fecundates the ovum. The constant con¬ 
traction of the vesicle seems opposed to the 
view that its function is that of merely fecun¬ 
dating the ovum, and Dujardin thinks it is 
connected with the function of respiration. 
Hitherto no spermatozoa have been found in 
these organs, although Doyere states that he 
has found zoospores in the tardigrade In¬ 
fusoria. The spermatic tubes are seen in 
Rotifer vulgaris (fig. 299. i, i), in Hydatina 
senta (fig. 293. h), and Notommata myrmeleo 
(Jig. 303. f,g). 
After the extrusion of the ova from the 
cloaca in many species, they are attached to 
the lorica, as in Brachionus pala (fig. 296,/.), 
in the same way as in some Crustacea. The 
rapidity with which the ova are produced is 
very great ; and one individual, in the course 
of a few days, will be the parent of many mil¬ 
lions. Their reproductive powers, however, 
are small compared with those of Polygastria. 
In this brief sketch we have occasionally 
alluded to the affinities of the Rotifera, and 
we think that there can be little doubt, that 
these are decidedly with the Articulata, stand¬ 
ing perhaps between the cilio-branchiate Polyps 
on the one side, and the Cirrhopoda on the 
other. Ehrenberg has summed up the general 
relations of these creatures in the following 
manner. They are 
Polygastria, with a single intestinal canal, 
without the power of spontaneous fission. 
Acalepha, with a simple intestinal canal, and 
rotatory organs. 
Nematoid worms, with rotatory organs and 
united sexes. 
Bryozoa, without gemmiparous reproduc¬ 
tion. 
Mollusca, without vascular pulsations. 
Entomostraca, without pulsation or arti¬ 
culated feet, and hermaphrodite reproduction. 
Fishes without a backbone or a heart, and 
with rotatory organs and united sexes. 
Bibliography. — Leeuwenhoek, Philosophical 
Transactions, 1701—1704. Baker, Employment of 
the Microscope. London, 1753. Bory St. Vincent, 
Dictionnaire Classique d’Histoire Naturelle, art. 
Rotiferes. Ehrenberg, Infusions-thierchen. Berlin, 
1838. Pritchard, Infusoria, living and fossil. London, 
1845. Doyere, Memoire sur les Tardigrades ; Ann. 
des Sc. Nat. 1842. Owen, Lectures on Comparative 
Anatomy, vol. i. London, 1843. Grant, Outlines 
of Comparative Anatomy. London, 1843. T. Bymer 
Jones, A general Outline of the Animal Kingdom. 
London, 1841. Dujardin, Histoire Naturelle des 
Zoophytes, Infusories. Paris, 1843 ; Report on the 
Progress of Zoology, 1842, published by the Ray So¬ 
ciety. Oken, Phisio-Philosophy, Ray Society, 1847. 
Mantell, Thoughts on Animalcules. London, 1846. 
Carpenter, Cyclopaedia of Natural Science. London, 
1847. (Edwin Lankester.) 
RUMINANTIA. (See Supplement.) 
SALIVA (la Salive, Fr.; der Speichel, 
Germ. ; la Sciliva, Ital.). — The saliva is a 
fluid secreted by a series of glands placed 
about the maxillary region. These glands, 
viz. the parotids, submaxillaries, and sub¬ 
lingual s, pour their secretions into the cavity 
of the mouth on either side. In consequence 
of this arrangement, it has always been a 
matter of difficulty to obtain saliva in a per¬ 
fectly pure state, the secretion of the mouth 
interfering, by admixture, with the exhibition 
of the natural qualities of the saliva, and more 
especially with its microscopic characters. It 
occasionally happens that the fluid can be ob¬ 
tained more directly from the gland in cases 
of salivary fistula affecting the parotid duct, 
but it is to be doubted whether we ought to 
look for the secretion in its normal state in 
such instances. No attempts have, as yet, 
been made to determine whether or not saliva, 
as obtained from the different glands, is iden¬ 
tical in character ; but so far as general ob¬ 
servation guides us, there appears no variation 
in its constitution as secreted from these dif¬ 
ferent sources. 
Quantity.—The quantity of saliva secreted 
during the day has never been very accurately 
ascertained. It has been said that about twelve 
ounces are produced during the twenty-four 
hours, but it is highly probable that much more 
than this is excreted by the adult in health. 
The data for the statement above mentioned 
are most imperfect. Mitscherlich made expe¬ 
riments on a patient suffering from fistula of 
the stenonian duct, and succeeded in obtaining 
about 2£ ounces troy of saliva from the one 
parotid in twenty-four hours. The saliva col¬ 
lected during the same time from the mouth 
amounted in this experiment to six times 
more than that collected from the one gland : 
we may, therefore, conclude that the subject 
of this experiment was secreting from 16 
to 20 ounces troy of saliva during the twenty- 
four hours. Mitscherlich observed that when 
the nerves were not excited by the motion of 
the muscles of mastication, or of those of the 
tongue, no saliva flowed, but that motion of 
these parts induced secretion. 
The presence of food in the mouth caused 
a rapid flow of saliva, which was more espe¬ 
cially noticed when the first portions were in¬ 
troduced. Long mastication appeared to 
cause excessive secretion, and the more sti¬ 
mulating the nature of the food, the larger 
was the quantity of saliva produced. 
The uses of the saliva will be best con¬ 
sidered when we have described its general 
qualities. 
Physical qualities. — The constitution of 
saliva has been investigated by several che¬ 
mists. It possesses the following general 
physical characters : — When freshly ob¬ 
tained from the mouth it is opalescent, vis¬ 
cid, and colourless. It separates by rest 
into an upper stratum of clear fluid, and a 
lower portion made up of the same fluid in 
admixture with epithelium scales and mucus. 
Under the microscope, saliva shows the pre¬ 
sence of epithelium scales swollen mucus 
globules, and substances of various forms, ap¬ 
parently shreds of scales and ruptured cells. 
There are also fatty particles, varying in size, 
and bright granules. Some of the mucous
        

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