ABSTRACT
The induction of a supernumerary pharynx in a planarian
Incisions are made in the prepharyngeal region of Dugesia lugubris. These incisions are repeated every day.
When the nerve trunks are regularly cut, a supernumerary pharynx may appear at the level of the incisions, on condition that these incisions are far enough from the origin of the host pharynx.
However, even at large distances, the pharyngeal region exerts an inhibitory effect on the regeneration of such a pharynx: 20 days are necessary for its differentiation, and it is always smaller than the host pharynx.
It seems that the nerve trunks play, one way or another, a role in the induction of the supernumerary pharynx, but it cannot be determined what role they play. The nature of inhibition is not certain.
These results are compared to those obtained by other authors.
