FUNCTIONAL ClIANChS IN STRUCTURE 79 



the piles' of cisternae in the centrosphcre region represent the membrane depot 

 of the cell. Finally we should consider that the two membranes involved in the 

 process, the one at the cell surface and the one in the centrosphere region, are 

 probably related in their chemistry or in their molecular architecture. Evidently 

 all these assumptions should be taken for what they are: mere hypotheses to be 

 tested by future experimentation. 



In conclusion, I have presented three examples in which noticeable changes 

 affecting either the relationship, or the structure, or the location ot a number of 

 cell components have been detected by electron microscopy. Experimental condi- 

 tions and complementary biochemical information indicate that the changes de- 

 scribed are functional modulations of the structures under consideration. 



In my belief, these findings clearly support the thesis that the electron micro- 

 scope can be a useful tool in physiological research at the cellular or intracellular 

 level. 



REFERENCES 



1. Babkix, R. p. Secretory Mer/uuiisni of the Digestire Glands (20(1 ed.). New York: Hoebcr, 

 1950. 



2. Bracket, J. Arch. Biol. 53: 207, 1941-42. 



3. Brachet, J. In: The Nucleic Acids, editetl by E. Chargaff and J. N. Davidson. New York: 

 Acad. Press, 1955, Vol. 2:475. 



4. Brandt, P. W. Exper. Cell Res. 15: 300, 1958. 



5. Caspersson, T. Cell Growth and Cell Function. New York: Norton, 1950. 



6. Chapman-Andresen, C. and D. M. Prescott. Conipt. rend. lah. Carlsberg, Ser. chim. 30: 



57. 1956. 



7. Claude, A. In: Fine Structure of Cells. Groningen: P. Noordhoff, 1955, p. 307. 



8. Farquhar, M. G. and S. R. Wellincs. /. Biophys. Biochem. Cytol. 3: 319, 1957. 



9. Gey, G. O. The Harvey Lect. 50: 154, 1954-55. 



10. Green, D. E. Biol. Rev. 29: 330, 1954. 



11. Heidenhain, R. Arch. ges. Physiol. 10: 557, 1875. 



12. Heidenhain, R. In: Handhuch der Physiologic, edited by L. Hermann. Vogel Verlag, 

 5/1: 173, 1883. 



13. Hokin, L. E. Biochim. et biophys. acta 18:379, i955- 



14. Holter, H. and J. M. Marshall. Compt. rend. lah. Carlsberg, Ser. chim. 29: 7, 1954. 



15. Knox, E. W., B. N. Noyce and V. H. Auerbach. /. Biol. Cheni. 176: 117, 1948. 



16. Laird, A. K. and A. D. Barton. Biochim. et biophys. acta 27: 12, 1958. 



17. Lansing, A. J. /. Histochem. Cytochem. i: 265, 1953. 



18. Lehninger, a. L. and E. R. Kennedy. /. Biol. Chem. 179: 957, 1949. 



19. Lewis, \V. H. Harvey Lect. 31: 214, 1935-36. 



20. Littlefield, J. W., E. B. Keller, J. Gross and P. C. Zami.cnik. /. Biol. Chem. 217: 

 III, 1955. 



21. LoFTFiELD, R. B. Prog. Biophys. Biophys. Chem. 8: 347, 1957. 



22. Ma, W. C. Am. /. Anat. 36: 215, 1925. 



23. Marshall, J. M. Exper. Cell Res. 6: 240, 1954. 



24. Palade, G. E. Anat. Rec. 114: 427, 1952. 



25. Palade, G. E. /. Histochem. Cytochem. i: 188, 1953. 



