No abstract

The amputations of the hydra in the hypostomal region have been performed. The material has been fixed in various time intervals after the amputation (from 5 min to 19 hours).The healing of the wound is done with the participation of all endodermal cells, the regeneration process with the help of zymogenic cells which dedifferenciate into neoblasts, and the neoblasts develop into ectodermal cell elements by differentiation. The old ectoderm does not take part in forming the young ectoderm in the wound area.The participation of endoderm in healing the wound and in the regeneration has been stated by the method for the acid phosphatase. It is supposed that the zymogenic cells also in normal hydra supply the ectoderm with new cells.

Asexual, non-budding hydras were treated in the 1∶75000 solution of E 39 solubile (Bayer). They were feeding, growing and budding for six days. The interstitial cells found in the ectoderm at the moment of treatment differentiated into cnidoblasts during that period. The cells that happened to be in the gastroderm at that time, differentiated into interstitial cells which were not able to cross the mesoglea due to the E 39 activity. In the gastroderm a great number of cnids appeared.These observations support the hypothesis that in normal hydra the interstitial cells formed by the dedifferentiation of gland cells pass into the ectoderm. There they are transformed into cnidoblasts which pass into the mesoglea. Prom the gastroderm the cnidoblasts come into the ectoderm of the tentacles through endodermal cells and the coelenteric fluid.

Summary:Within 24 h time, Torak EC 24 in 10 mg/l and 30 mg/l concentrations causes the worst damage immediately after treatment. In the treated hydras, a considerable state of contraction, a damage of tentacles and the hypostome as well as a damage of intracellular membranes and cellular organelles was observed. Besides, during the experiment, the treated hydras in both concentrations used were budding more intensely than the control.

The regeneration of the hypostome and the foot of a cross-cut Hydra which was exposed to phosalone 4 and 6 hours after cutting has been studied. The regeneration of the hypostome of the P part had its regular course of changes in the differentiation and dedifferentiation of zymogen cells. But, a certain number of regenerated hypostomes were deformed in relation to the regenerated hypostomes of the control hydras. H parts regenerated the foot slightly more slowly than the control. Due t o the effect of phosalone, the hypostomes of H parts are seriously damaged. Their regeneration also resulted in malformations.