. The cell; outlines of general anatomy and physiology. Cells; Anatomy; Physiology; Cells; Anatomy; Physiology. THK VITAL PROPERTIES OF THE CELL 159 Under such circumstances the cells are filled with drops of oil (oilJ seeds), with granules of various albuminous substances (vitellin, gluten, aleuron), with crystalloids of proteinaceous sub- stance, or with starch granules, about which more will be said later. The above-mentioned internal plasmic pi'oducts being only tem- porarily accumulated during metabolism before being utilised, vary considerably in composition, but there are others which a
. The cell; outlines of general anatomy and physiology. Cells; Anatomy; Physiology; Cells; Anatomy; Physiology. THK VITAL PROPERTIES OF THE CELL 159 Under such circumstances the cells are filled with drops of oil (oilJ seeds), with granules of various albuminous substances (vitellin, gluten, aleuron), with crystalloids of proteinaceous sub- stance, or with starch granules, about which more will be said later. The above-mentioned internal plasmic pi'oducts being only tem- porarily accumulated during metabolism before being utilised, vary considerably in composition, but there are others which attain a higher degree of organisation, and which participate permanently in the functions of the cell. To such belong the internal skeletal structures of the protoplasm, the various sub- stances in plant cells, described under the common name of trophoplasts, the cnidoblasts of Coelenterata, and, finally, the sheaths of the muscle and nerve fibres, etc. Internal skeletons are found in the bodies of a large number of Protozoa, but especi- ally in great variety and beauty in Radio- larians. They consist sometimes of regularly arranged spicules, sometimes of a fine, open trellis-work, and sometimes of a com- bination of the two kindsof structures (Fig. 66). In some families of Radiolarians they are composed of an or- ganic substance which is soluble in acids and alkalies, but in most cases, on the contrary, they consist of silicious material which is united to an organic substratum, just as, in the bones of Vertebrates, the phosphates are united with the ossein. In each species the skeleton has a constant and characteristic structure, and follows cei'tain fixed laws during the process of its development (Richard Hertwig, 5, 40). Under the name trophoplasts, the highly organised difi^eren- tiated products of vegetable protoplasm are included ; these occur. Fi&. 66.—HnHomma erinnceus (from R. Hertvrisr, Zool., Fig. 82) : a external, i internal trellis work ; clc central capsul
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