Note 24 — Chapter IV · THE MORPHOLOGICAL COMPOSITION OF ANIMALS.

Though this was doubtful in 1865 it is no longer doubtful. In an individual Ctenodrilus monostylus, which multiplies by dividing and subdividing itself, “parts arise which are destitute of both head and anus and at times consist of only a single segment.” In another species, C. pardalis, there is separation into many segments; and each segment before separating forms a budding zone out of which other segments are afterwards produced, completing the animal (Korschelt and Heider, Embryology, i, 301–2).