638 R. J, GOLDACRE 



Acknowledgments 



This investigation has been supported by grants to the Chester Beatty 

 Research Institute (Institute of Cancer Research : Royal Cancer Hospital) 

 from the Medical Research Council, the British Empire Cancer Campaign, 

 the Jane Coffin Childs Memorial Fund for Medical Research, the Anna 

 Fuller Fund, and the National Cancer Institute of the National Institutes 

 of Health, U.S. Public Health Service. 



References 



1. Blowers, R., Clarkson, E. M., and Maizels, M.,jf. Physiol. 113, 228 (1951). 



2. Brown, R.,y. exp. Bot. 4, 197 (1953). 



3. Danielli, J. F., Proc. roy. Soc. B 142, 146 (1954); see also Danielli, J. P., 

 Symp. Soc. exp. Biol. 6, i (1952). 



4. Goldacre, R. J., and Lorch, I. J., Nature, Loud. 166, 497 (1950). 



5. Goldacre, R. J., Int. Rev. Cytol. I, 135 (1952). 



6. Goldacre, R. J., Nature, Lond. 172, 594 (1953). 



7. Goldacre, R. J., Exp. Cell Res. Suppl. 8, i (1961). 



8. Kamiya, N., and Kuroda, K., Bot. Mag., Tokyo 69, 545 (1956). 



9. Kamiya, N., and Kuroda, K., Proc. imp. Acad. Japan 33, 201 (1957). 



10. Nakao, M., Nakao, T., and Yamazoe, S., Nature, Lond. 187, 945 (i960). 



11. Prescott, D. M., Nature, Lond. 172, 593 (1953). 



12. Pulvertaft, R. J. V., 7- d'"- Path. 2, 281 (1949). 



13. Ts'o, P. O. P., Bonner, J., Eggman, L., and Vinograd, ].,y. gen. Physiol. 39, 



325 (1956). 



Discussion 



ScHOFFENiELS : As an extension of what you have said in your introduction 

 about some models of active transport presented by Danielli, I would like to 

 consider the following mechanical model we have been working with lately. It is 

 made of two chambers separated by a hole shaped like a funnel. Now if we place 

 small steel balls in both chambers and if we shake the whole apparatus we get an 

 accumulation of balls in the chamber facing the large apperture of the funnel. 

 This could well be, among many others proposed, a model for a cellular mechanism 

 of active transport. This would imply the existence of a contractile structure in the 

 cellular men.brane as well as the presence of a funnel-like pore exhibiting 

 specificity toward an ion species. 



Allen: I don't think there is any doubt that Dr. Goldacre 's observations on 

 dye accumvilation in the amoeba are correct. It was described also independently 

 by Dr. Okada in Japan, 1930, but dye accumulation is subject to alternative 

 interpretations. In fact, one might say that the dye accumulation phenomenon 

 is compatible with at least three hypotheses. First, as Dr. Goldacre pointed out in 

 his paper in 1950, the entire surface of the amoeba (i.e. the plasmalemma and the 

 outer layer of ectoplasm) adsorbs quite a bit of dye ; by the time the amoeba has 

 moved one cell length, this adsorbed dye has accumulated in the tail. Now if you 



