. The cell; outlines of general anatomy and physiology. ication. That the starch grains grow by the deposition of new layersupon the surface, that is by apposition, may be deduced from astatement of Schimpfers. He observed, that around the corrodedcentres of starch grains whose surfaces had been dissolved awaynew layers had been deposited. Strasburger is of opinion that starch grains may be occasionallyproduced in the protoplasm itself, without the intervention ofspecial starch-forming corpuscles. He found them in the cells ofthe medullary rays of Gcmiferre, during their early stages ofdevelop
. The cell; outlines of general anatomy and physiology. ication. That the starch grains grow by the deposition of new layersupon the surface, that is by apposition, may be deduced from astatement of Schimpfers. He observed, that around the corrodedcentres of starch grains whose surfaces had been dissolved awaynew layers had been deposited. Strasburger is of opinion that starch grains may be occasionallyproduced in the protoplasm itself, without the intervention ofspecial starch-forming corpuscles. He found them in the cells ofthe medullary rays of Gcmiferre, during their early stages ofdevelopment, as minute granules, embedded in the strands of theplasmic network. As they grew larger they were to be plainlyseen situated in the plasmic cavities. These cavities have highlyrefracting walls, upon which microsomes are situated. One of the most remarkable of the internal plasmic productsis the nematocyst (Fig. 70), which functions in Gaelenterata asa weapon of attack, in the cnidoblasts, which are distributed THE VITAL PROPERTIES OF THE CELL 165. throughout the ectoderm. It consists of an oval capsule (a and6), which is formed of a glistening substance, and which has anopening in that end which is directed towards the external sur-face. The internal surface is lined with a delicate lamella which,at the edge of the opening, merges with the sheath of the cap-sule ; the structure of this sheath is frequently very complicated(cf. Fig. 70 a, b). In the figure, this sheath consists of a verydelicate filament and of a broad, conical,proximal portion, which is situated in theinterior of the capsule, and is provided withshorter and longer barbs. The filamentstretches from the end of the conical por-tion, and is wound spirally round andround it several times ; the free, internalcavity is filled with an irritating secretion ;the protoplasm, which borders on the ne-matocyst, is differentiated to form a con-tractile envelope, which also has an open-ing to the exterior (Schneider V. 45
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