. Electro-physiology. Electrophysiology. ELECTRO-PHYSIOLOGY CHAP. that these structures are transitional stages between pseudopodia and muscle-fibrils proper. If we examine a large transparent Vorticella under the high power, it is easy to detect delicate, converging fibrils just below the surface ; they run parallel with the axis of the body, and are often finely varicose. Here we undoubtedly have a differentiation product of the ectoplasm (Fig. 1), whether—with Blitschli (3)— we regard these fibrils merely as a longitudinal series of cells within the otherwise alveolar protoplasm, or as a sp
. Electro-physiology. Electrophysiology. ELECTRO-PHYSIOLOGY CHAP. that these structures are transitional stages between pseudopodia and muscle-fibrils proper. If we examine a large transparent Vorticella under the high power, it is easy to detect delicate, converging fibrils just below the surface ; they run parallel with the axis of the body, and are often finely varicose. Here we undoubtedly have a differentiation product of the ectoplasm (Fig. 1), whether—with Blitschli (3)— we regard these fibrils merely as a longitudinal series of cells within the otherwise alveolar protoplasm, or as a special structural arrangement. These fibrils (myonema] converge towards the junction of the stalk, there, in most cases, uniting into a cylindrical filament, which appears fibrillated throughout in optical transverse section. Certain of the Heterotricha (Stentor, S'pirostomuni) and Holotricha (Holo- pliyra, Prorodon, Opaliniden) are char- acterised by a much more pronounced development of muscular fibrils. Those of Stentor, isolated by Engelmann, were as much as I/* in diameter. There were even indications of a finer struc- ture, a kind of transverse striation (3, p. 1000). Lieberkiihn recognised the fibrils of Stentor as contractile elements. He observed that \vhile invariably straight in contracted Stentors, they assume an undulatory appearance as soon as the infusorium begins to lengthen, becoming elongated during relaxation. As the animal grows longer, the waves become flatter. The fibrils eventually become quite straight again, and are more and more drawn out with continued extension. In the foot, which is most protracted, they lose all separate identity; in the rest of the body they resemble lines of excessive fineness. " If, as often happens, the animals shrink slowly together during several seconds, instead of contracting suddenly, the fibrils, instead of being short, thick, and straight at the maximum of contraction, will be distinctly wave-like, and not p
Size: 1250px × 2000px
Photo credit: © The Book Worm / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bo, bookcentury1800, bookdecade1890, bookpublisherlondonmacmillan
