Report on the Radiolaria Collected by H.M.S. Challenger During the Years 1873-1876, First Part: Porulosa (Spumellaria and Acantharia): Report on the Scientific Results of the Voyage of H.M.S. Challenger During the Years 1873-76, Vol. XVIIIHaeckel, Ernst
Science
Report on the Radiolaria Collected by H.M.S. Challenger During the Years 1873-1876, First Part: Porulosa (Spumellaria and Acantharia): Report on the Scientific Results of the Voyage of H.M.S. Challenger During the Years 1873-76, Vol. XVIII
Haeckel, Ernst
Radiolaria
80. _The Endoplasm of the Cannopylea._--The intracapsular protoplasm of the
PHÆODARIA or CANNOPYLEA is distinguished from that of the other three
legions by several characteristic peculiarities, which are very important,
since they stand in causal relation to the typical structure of the
capsule-membrane and in particular of its {l}remarkable aperture. In the
case of many and perhaps of all PHÆODARIA the endoplasm is differentiated
into a granular medullary and a thin fibrillar cortical layer, the former
of which usually encloses numerous small vacuoles, while the latter
contains muscular fibrillæ. In the voluminous central capsule of large
PHÆODARIA the whole cortical layer of the endoplasm, which lies immediately
below the delicate inner capsule-membrane, sometimes appears delicately and
regularly striated, and most distinctly so under the apertures, towards the
centre of each of which the dark striæ are radially directed (see note A,
below). These striæ are probably contractile muscular fibrillæ; or
"myophanes," by whose contraction the openings are voluntarily widened. In
the Tripylea this fibrillar star is much more strongly developed under the
astropyle (the main opening) than under the parapylæ (or accessory
openings); and probably the peculiar radial structure of the operculum of
the former is due to the stronger development of these radial fibrils
(being their impression). In many PHÆODARIA, indeed, the fine myophane
fibrils are only visible under the apertures, whilst in others they form a
continuous fibrillar cortical layer on the whole inner surface of the inner
capsule-membrane; the fine fibrillæ run meridionally from one pole of the
main axis to the other; perhaps the whole central capsule may change its
form in consequence of their contractions. The medullary portion of the
endoplasm, which lies below this thin cortical layer, is usually finely
granular in the PHÆODARIA, and permeated by numerous spherical vacuoles,
which are noteworthy from their equal size and regular distribution. Each
clear vacuole usually contains a dark shining fat-granule, more rarely a
group of such granules (see note B). Compare § 60, and Pl. 101, figs. 1-3;
Pl. 104, figs. 1, 2; Pl. 111, fig. 2; Pl. 128, fig. 2, &c.
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