Acanthometra form a special order within the legion of Acantharia. These Radiolaria live in huge amounts hovering at the sea surface; they are of very minor size, usually visible only under the microscope. Acantharia are distinguished from other Radiolaria by the peculiar chemical and morphological composition of their skeleton that consists of a very solid and elastic organic substance (Acathin). The twenty prickles/flagella that compose the skeleton emanate from the centre of the unicellular body and are distributed most regularly following a most peculiar law. According to this ‘positioning law’ – law of Ikosakanth – the tips of the twenty radial flagella fall in the shape of five parallel circles, corresponding, according to their position, to the equator, the two tropic and the two polar circles of the earth. The four flagella of each circle are lying in two meridian planes that are perpendicular to each other. The eight ‘polar flagella’ and the four ‘equatorial flagella’ are lying in the same two meridian planes. The eight ‘tropical flagella’, however, stand in two different meridian planes that cross each other in a right angle, cutting through the latter in an angle of 45 decrees. The vertical axis of the globe, in the centre of which lies the circular central capsule of Acantharia (here coloured in yellow), does not have any flagella. The gelatinous cover (Calymma) that surrounds the spore-forming central capsule is interspersed with Pseudopodia that emanate from it (fig. 1-5). Pseudopodia are used for sensing and locomotion as well as for the capturing and digesting of food; they do not emanate in a uniform way from the inner central capsule (as in Spumellaria, plate 11) but are distributed in regular lines on the planes in between the skeletal flagella; the latter are used as protecting arms and hovering apparatuses.
Translation of the original German introduction by Ernst Haeckel:
Phylum of Protozoa (Urtiere); - class of Rhizopoda (Wurzelfüßer); - subclass of Radiolaria (Strahlinge); - legion of Acantharia (Actipyleae); - order of Acanthometra (Stachelstrahlinge).
Translation by VR Translators Bangalore
This is one of the 100 pop science biology illustrations that were published from 1899 – 1904 in Leipzig by Ernst Haeckel through Verlag des Bibliographischen Instituts.
We've scanned the original lithography at 1200dpi on the Epson A3 scanner of A3 scanner huren. You can download a 400dpi JPEG here.