. The dynamics of living matter . Figs. 51-54. — After Morgan. Successive stages in the regeneration of the oblique piece adcf of Fig. 50. does that this is due to purely mechanical conditions. The head of such an oblique piece is asymmetrical, the one side ab being less stretched than the other side be. The higher tension of the piece be will have the effect of bringing b nearer c. The reverse is true for the tail def, and the effect will here be that e will be pulled nearer d. In this way purely mechanical conditions are responsible for the fact that the soft tissues of the animal are gradua
. The dynamics of living matter . Figs. 51-54. — After Morgan. Successive stages in the regeneration of the oblique piece adcf of Fig. 50. does that this is due to purely mechanical conditions. The head of such an oblique piece is asymmetrical, the one side ab being less stretched than the other side be. The higher tension of the piece be will have the effect of bringing b nearer c. The reverse is true for the tail def, and the effect will here be that e will be pulled nearer d. In this way purely mechanical conditions are responsible for the fact that the soft tissues of the animal are gradually restored to their true orientation.* It was of interest to find out whether heteromorphosis could be pro- duced in Planarians. At my request Dr. Van Duyne undertook experi- ments in this direction and succeeded in a few Figure 55 shows one of these instances. On the right side of the animal the posterior part had been cut off. A new head which was directed backward was regenerated in place of the amputated part. Morgan was more suc- cessful later on. He obtained a larger number of heteromorphoses by cutting short pieces out of a Planarian than by cutting out long * It is in mv opinion not only unnecessary but directly confusing to introduce for the explanation of these phenomena of restitution such mystical forces or conceptions as Noll's " Morphassthesia," and similar things. t Van Duyne, Pjluger's Archiv, Vol. 64, p. 56Q, i8q6. % Morgan, Archiv fur Entiuickelungsmeckanik, Vol. 17, p. 683, 1904.
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