The dynamics of living matter . dynamicsofliving1906loeb2 Year: 1906 2IO DYNAMICS OF LIVING MATTER longitudinal elements to which reference was just made. If a lateral incision be made in the body at c, not too far from the openings, ocelli will be formed at each free end of these elements. Here the longi- tudinal elements show heteromorphosis, inasmuch as they are capable of forming ocelli at both ends. I am inclined to believe that in each of these cases the individual longitudinal element represents a conductor for nutritive material or specific morphogenic substances in the sense of Sachs
The dynamics of living matter . dynamicsofliving1906loeb2 Year: 1906 2IO DYNAMICS OF LIVING MATTER longitudinal elements to which reference was just made. If a lateral incision be made in the body at c, not too far from the openings, ocelli will be formed at each free end of these elements. Here the longi- tudinal elements show heteromorphosis, inasmuch as they are capable of forming ocelli at both ends. I am inclined to believe that in each of these cases the individual longitudinal element represents a conductor for nutritive material or specific morphogenic substances in the sense of Sachs. It must remain undecided for the present whether this flow occurs through the hollow space or through the tissue or certain cells of the tissue. 4. Regeneration and Heteromorphosis in Fresh-water Planarians It had been known for a long time that if the head and the tail be cut off from a fresh-water Planarian, at the front end a new normal head, at the back end a new tail, will be regenerated (Fig. 49). Morgan* made the interesting observation that if a piece acdf be cut obliquely (Fig. 50) instead of at right angles to the longitudinal axis from a Fig. 49.—After Morgan. Planarian, a tiny head is formed at the foremost corner of the piece a and a tiny tail at the hindmost corner /, Fig. 51. Why is it that in the oblique piece the head is formed in the corner and not all along the cut surface as is the case when the cut is made at right angles to the longitudinal axis? I am inclined to believe that the right answer to this question has been given by Bardeen has pointed out the apparent role that the circulatory (or so-called digestive) canals in Planarians play in the locali- zation of the phenomena of regeneration, inasmuch as the new head always forms symmetrically at the opening of the circulatory vessel * Morgan, Regeneration, New York, 1901. t Bardeen, Am. Jour. Physiology, Vol. 5, p. I, 1901 ; and Archiv fiir Entwickelungs- meckanik, Vol. 16, p. 1, 1903.
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