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
79. _The Endoplasm of the Monopylea._--The intracapsular protoplasm of the
NASSELLARIA or MONOPYLEA is distinguished from that of any of the other
three legions by the development of a quite peculiar fibrillar structure,
the axial "pseudopodial cone," which may shortly be termed the "podoconus"
(foot-cone). Since this is in direct correlation with the peculiar
structure of the capsular opening, the large "porochora," which is situated
at the basal pole of the main axis, it is quite as characteristic of the
legion as the latter itself (see note A). The podoconus is primitively a
vertical regular cone whose circular base occupies the horizontal porochora
or "basal porous area" of the central capsule, while its vertical axis
coincides with that of the latter. The apex of the cone, usually somewhat
rounded off, is therefore directed towards the aboral or apical pole of the
central capsule and separated from it by a larger or smaller interval. In
this interval the nucleus originally lies (as in Pl. 51, fig. 13; Pl. 98,
fig. 13); but it is usually displaced subsequently and lies excentrically.
The cone is of very variable height; on an average its vertical height is
about equal to the diameter of its horizontal base; these dimensions are,
however, dependent upon the form of the central capsule; the height being
greater in slender ovoid or conical capsules, and less in depressed
sphæroidal or discoidal ones, than the diameter of the base. The podoconus
consists of differentiated endoplasm, which becomes more deeply stained by
carmine and offers greater resistance to solvents than the surrounding
finely granular protoplasm. The apex, especially, becomes very intensely
stained. It always exhibits a very characteristic fine but distinct
striation, numerous straight radial lines diverging from the apex of the
cone towards the base. The number of these striæ appears to correspond with
that of the vertical rods in the porochora, and each of these latter stands
apparently in direct communication with the basal end of an apical stria (§
59). These threads are probably differentiated constant contractile threads
of endoplasm, or even myophanes, comparable with the contractile cortical
threads of the CANNOPYLEA and the permanent axial threads of the ACTIPYLEA.
The numerous modifications, {xlix}undergone by the form and contents of
the central capsule in the different groups of MONOPYLEA, especially those
due to the formation of the skeleton, are not without influence upon the
podoconus. The most important divergencies from the above described primary
form are the following:--(1) The vertical axial cone becomes oblique, its
axis inclining in the sagittal plane and approaching either the dorsal or
the ventral wall of the capsule; the cause of this appears to be usually
the excentric development of the growing nucleus or the formation of a
large oil-globule. (2) The smooth mantle of the podoconus becomes divided
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