M73 



Studies in Dedifferentiation. IV. Resorption 

 and Differential Inhibition in Obelia and 

 Campanularia. 



By 



J. S. Huxley, M.A., 



and 



G. R. de Beer, B.A., B.Sc. 



With Plate 26 and 7 Text-figures. 



Introduction. 



It is well known that among the processes whereby an 

 organism is developed all are not constructive, but some may 

 involve the demolition of certain structures which may either 

 have ceased to subserve a useful function, or may actually 

 hinder further development. A familiar example is the gill 

 or tail of Amphibian larvae at metamorphosis. 



In normal circumstances this retrogression only affects 

 certain organs, but recently it has been found possible to 

 produce this effect experimentally in whole organisms (Driesch, 

 1906, &c.). 



Protozoa, Planarians, Sponges, Ascidians, and Coelenterates 

 will under certain conditions give the retrogressive effect, as 

 evidenced by the work of Lund (1917), Child (1904), Maas 

 (1910), Huxley (1921 h), Loeb (1900), and others. 



Following some observational work by one of us (J.S.H.), 

 it was thought that quantitative experiments involving the 

 subjection of organisms to different concentrations of poisons 

 might give interesting results. One of the authors (G.E. de B.) 

 accordingly performed some experiments on Obelia geni- 

 culata which will be described below. 



