. Elementary text-book of zoology. Zoology. BHIZOPODA. 181 by holes, to shelter and protect the body (Foratninifera, Radiolaria\ In the Infusoria the sarcode body is bounded by an external mem- brane, and is capable of quick and varied locomotion by means of the movements of the cilia, hairs, bristles, etc., which it possesses. The solid nourishing matter is taken in through a mouth, and the remainder, after digestion, passes out through an anal aperture. CLASS I.— RHIZOPODA.* Protozoa without external investing membrane, the parenchyma of which protrudes and retracts jwocesses ; as a rule, a
. Elementary text-book of zoology. Zoology. BHIZOPODA. 181 by holes, to shelter and protect the body (Foratninifera, Radiolaria\ In the Infusoria the sarcode body is bounded by an external mem- brane, and is capable of quick and varied locomotion by means of the movements of the cilia, hairs, bristles, etc., which it possesses. The solid nourishing matter is taken in through a mouth, and the remainder, after digestion, passes out through an anal aperture. CLASS I.— RHIZOPODA.* Protozoa without external investing membrane, the parenchyma of which protrudes and retracts jwocesses ; as a rule, a calcareous shell or silicious skeleton is secreted. The body-substance of these animals, the shells of which were described as Foraminifera or Polythalamia, long before their living contents were known, consists of sarcode, and is without any boundary mem- brane. The body- substance, which is richly granulated and contains p i g- rnent, contracts slowly and sends out at the same time fine thread-like rays (fig. 120), for the most part of a semi-fluid consistency (pseudopodia); and these serve not only as a means of movement but also for the reception of nourishment. The pseudopodia may, how- * Dujardin, "Observations sur les Rhizopodes" (Comjrft's triidu*. 1835). Ehrenberg, '• Uber noch jetzt zahlreich lebende Thierarten der Kreidebihlung und den Organismus der Polythalamien" (Alkdndluni/ (Jcr Aluid. zu Berlin, 1839). Max Sigm. Schultze, "Uber den Orga/iismus der Pulythalamien" (Leipzig. 1854). Job. Miiller. '' Uber die Thalassicolen, Polycystinen und Acan- thometren" (1858). E. Haeckel, "Die Radiolarien" (Eine Monographic. Berlin. 1862).. FIG. 120.—Optical section through portion of the sarcode body of Actinosplmerium Elchhoniii (after Hertwig and Lesser). N, nuclei in the endosark, from which the vacuolated ectosark is clearly dis- tinguishable. In the centre of the pseudopodia the axial thread is Please note that these
Size: 1705px × 1465px
Photo credit: © Paul Fearn / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookcentury1800, bookdecade1880, booksubjectzoology, bookyear1884
