Note 6 — Chapter XIII · The Wavy Path of the Ameba and the Spiral Paths of Ciliates and other Organisms

The gap between the rate of movement of a pseudopod and that of a flagellum is however very wide. Insofar as the character of the movement is concerned, pseudopods such as those of flagellipodia, probably resemble the flagella of the soil ameba and of flagellates. But the very much greater speed of contraction of a flagellum and the presence of a special organ (blepharoplast) at the base of the flagellum, and their connection with the nucleus, indicates that a special mechanism is necessary to cause the rapid contraction. A flagellum appears to be a pseudopod supplied with something like nerve tissue and a ganglion capable of setting free a rapid succession of impulses.