A Study of Normal and 



Abnormal Regeneration 



of Hydra' 



Dorothy B. Spangenberg 



Spcin^enherg Lcihoraiorics, Refugio, Texas 



One of the most challenging fields of developmental research 

 is the study of the regeneration of lost parts in lower animals. 

 This area of investigation is of special interest because most of 

 the processes involved in such regenerative phenomena (cell mi- 

 tosis, cell differentiation, cell migration, the interaction of cells or 

 tissues) are analagous to those taking place in most other forms of 

 development, and because these processes in lower animals can 

 be studied with relative ease. 



Hydra are particularly suited for this purpose since they are 

 able to regenerate lost parts rapidly and can be easily maintained 

 in the laboratory. Previous investigators of hydra regeneration 

 have placed a major emphasis on (a) the capacity of different 

 hydra parts to regenerate, (b) histological changes during normal 

 regeneration, (c) regulation following abnormal regeneration, and 

 (d) metabolic gradients in regenerating hydra. Recent investiga- 

 tions made in this laboratory of the regenerative ability of hydra 

 (as measured by the rate of regeneration of tentacles and the 

 number of tentacles regenerated) revealed that normally this 

 capacity varies even between strains of the same species of 

 hydra and can be markedly influenced by environmental factors 



^ These investigations were carried out at the Clayton Foundation Biochemical In- 

 stitute, The University of Texas, Austin, Texas. 



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