. The dynamics of living matter. Biochemistry; Reproduction; Regeneration (Biology). DYNAMICS OF REGENERATIVE PROCESSES 209 sary for their growth. In one experiment the oral disk of a Cerianthus was cut off ; very soon new tentacles began to grow at the top, and after having reached a certain size, an incision was made in the animal at d, Fig. 47. The tentacles above the incision between b and c, Fig. 47, collapsed in consequence and ceased to grow, while growth of the others between a and b continued. On the lower edge of the incision new tentacles began to grow. Child* has elucidated to some
. The dynamics of living matter. Biochemistry; Reproduction; Regeneration (Biology). DYNAMICS OF REGENERATIVE PROCESSES 209 sary for their growth. In one experiment the oral disk of a Cerianthus was cut off ; very soon new tentacles began to grow at the top, and after having reached a certain size, an incision was made in the animal at d, Fig. 47. The tentacles above the incision between b and c, Fig. 47, collapsed in consequence and ceased to grow, while growth of the others between a and b continued. On the lower edge of the incision new tentacles began to grow. Child* has elucidated to some extent these phenomena of turgidity. Every tentacle is a hollow cylinder, and this cylinder continues down- ward where it communicates with the body cavity. When liquid is pressed into the tube from the body cavity, the tentacles are stretched; but if the liquid leaves the tube, the tentacles relax also. If an incision is made below a tentacle into the wall of the body of a Cerianthus, no more liquid can be pressed into that tentacle, and it relaxes. Child con- firmed my observation, that regeneration of the tentacles in Cerianthus is no longer possible when they relax. He added a number of pretty demonstrations of the necessity of the turgidity of the tentacles for regeneration. He found, for instance, that if an incision is made into the foot of a Cerianthus and the edges of the wound are prevented from healing together the tentacles lose their turgidity and are no longer able to grow. He found, also, that the ten- tacles degenerate under such conditions. It is unknown at present how the turgidity can influence growth in the tentacles of an Actinian. The observations on Cerianthus are comparable with those on Tubularia if we realize that the body wall in Cerianthus consists of a series of hollow cylinders or spaces each of which ends in a tentacle. The idea of an animal body consisting of a series of comparatively independent longitudinal elements recommends itself also for
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