[65] A parallel case is found when a piece partially split in two at the anterior end ([Fig. 24]) produces one or two heads on each half, according to the extent of fusion of the new material that goes to form the new head or heads.
[66] See Lang (’88).
[67] See Zacharias (’86).
[68] See Hescheler (’97).
[69] The proglottids of the cestodes seem to be an exception, but they are little more than sacs filled with embryos at the time of their separation. How far regeneration may take place in the scolex, or young proglottids, is not known, but it is not improbable that some of the abnormal forms that have been described may be due to regeneration.
[70] Except for the protozoa.
[71] The Fisheries and Fishing Industries of the United States, Washington, 1887.
[72] “The American Lobster,” Bull. U. S. Fish Comm., 1895.
[73] Réaumur in 1742 records the first observations. Spallanzani also described the process, and many later writers have examined it.
[74] The phenomenon has been observed by Dalyell, Semper, Minchin, and others.