author's abstract of this paper issued 

 bt the bibliographic service, june 1 



IS THE THEORY OF AXIAL GRADIENT IN THE 



REGENERATION OF TUBULARIA SUPPORTED 



BY FACTS? 



MARIO GARCIA-BANUS 



From the Laboratories of the Rockefeller Institute for Medical Research 



In his book "Individuality in Organisms," C. M. Child assumes 

 the existence of ' metabolic gradients ' in a great number of species 

 of animals and plants, and on this assumption he builds a theory 

 of individuality. 



In the case of the hydroid Tubularia, which he uses extensively 

 to prove his theory, the metabolic gradient would lie in the axis 

 of the animal. 



The apical end of the metabolic gradient of the major axis is the 

 apical end of the hydranth and from there the rate (metabolic rate) 

 decreases basally through the hydranth. In the stem the metabolic 

 rate is lower than in the hydranth and there is a slight decrease in the 

 basal direction, but at the growing tip of the stolon there is a short 

 gradient in the opposite direction .^ 



Child has made no measurements of the rate of metabolism of 

 different regions of the stem of tubularia. What he really means 

 is that an excised piece of the stem of Tubularia regenerates a 

 new hydranth at the oral end the more rapidly, the nearer this 

 end lies to the original apex of the stem. Such differences he 

 assumes to be due to alleged differences in what he calls 'meta- 

 bolic rates.' We are therefore only concerned with the question 

 whether the regional differences in the rate of regeneration which 

 Child assumes in Tubularia really exist. 



If a piece is cut from a stem of Tubularia a new hydranth will 

 regenerate at each end, and, according to the old experiments of 

 Loeb, the oral end of the piece will, as a rule, regenerate the 



^ Child, C. M., Individuality in organisms. Chicago, 1915. 



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