MESENCHYMAL CELLS 



second cannot be wholly excluded and we have been inclined 

 to believe that something equivalent to transduction may 

 occur under special circumstances. It seems fantastic, how- 

 ever, to picture a constant transfer of information to primi- 

 tive non-functional cells when a much simpler and intrinsi- 

 cally more likely hypothesis is available. The clonal selection 

 hypothesis with, as an integral part, the assumption that 

 circulating cells, presumably lymphocytes, can on appro- 

 priate stimulation become proliferating mother cells, seems 

 almost ideally suited to allow a simple interpretation of the 

 body's capacity to store large amounts of immunological 

 information. 



REFERENCES 



BjORNBOE, M., GoRMSEN, H. & LuNDQ,visT, F. (1947). Acta path, microbiol. 



scand. 20, 649. 

 Coons, A. H., Leduc, E. H. & Connolly, J. M. (1955). J. exp. Med. 



102, 49. 

 Craddock, C. G., Valentine, W. N. & Lawrence, J. S. (1949). 



J. Lab. din. Med. 34, 158. 

 Dougherty, T. F. (1952). Physiol. Rev. 32, 379. 

 Fagraeus, a. (1948). Acta med. scand. Suppl. 204. 

 Farr, R. S. (195 1 ). Anat. Rec. 109, 515. 



Fischel, E. E., LeMay, M. & Kabat, E. A. (1949). J. Immunol. 61, 89. 

 Ford, C. E., Ilberry, P. L. T. & Loutit, J. F. (1957). J. cell. camp. 



Physiol. 50, Suppl. i, 109. 

 GowANs, J. L. (1957). Brit. J. exp. Path. 38, 67. 

 Hamilton, L. D. (1956). Nature, Lond., 178, 597. 



Hammond, C. W. & Novak, M. (1950). Proc. Sac. exp. Biol., N.T., 74, 155. 

 Marshall, A. H. E. (1956). Cytology and Pathology of Reticular Tissue 



(Oliver and Boyd, Edinburgh). 

 Maximow, a. & Bloom, W. (1948). Textbook of Histology (5th ed. 



Philadelphia). 

 Medawar, p. B. (1957). Ann. N.T. Acad. Sci. 68, 255. 

 Ortega, L. G. & Mellors, R. C. (1957). J. exp. Med. 106, 627. 

 Ottesen, J. (1954). Acta physiol. scand. 32, 75. 

 Speirs, R. S. (1956). J. Immunol. 77, 437. 

 Speirs, R. S. (1958). Ann. N.T. Acad. Sci. 73, 283. 

 Stevens, K. M. & McKenna, J. M. (1957). Nature, Lond., 179, 870. 

 Taliaferro, W. H. (1949). Annu. Rev. Microbiol. 3, 159. 

 de Vries, J. A. (1950). J. Immunol. 65, i. 

 Wesslen, T. (1952). Acta derm, venereol., Stockh., 32, 195, 265. 

 YoFFEY, J. M. & Courtice, F. C. (1957). Lymphatics, Lymph and Lymphoid 



Tissue (2nd ed. London). 



120 



