T certify that I have read this study and that in my 

 opinion it conforms to acceptable standards of scholarly 

 presentation and is fully adequate, in scope and quality, 

 as a dissertation for the degree of Doctor of Philosophy. 



( 



Q/n^ 



t 



u 



/James F. Preston, Chairman 

 Associate Professor of 

 Microbiology and Cell Science 



I certify that I have read this study and that in my 

 opinion it conforms to acceptable standards of scholarly 

 presentation and is fully adequate, in scope and quality, 

 as a dissertation for the degree of Doctor of Philosophy. 



Kenneth D. Noonan 

 Professor of Biochemistry 



I certify that I have read this study and that in my 

 opinion it conforms to acceptable standards of scholarly 

 presentation and is fully adequate, in scope and quality, 

 as a dissertation for the degree of Doctor of Philosophy. 



VI 1-/1 



d-t 



C / / 



Edward M. Hof f matin' 



Professor of Microb/Lology and 



Cell Science 



f 



I certify that I have read this study and that in my 

 opinion it conforms to acceptable standards of scholarly 

 presentation and is fully adequate, in scope and quality, 

 as a dissertation for the degree^-oTf Doctor of Philosophy. 



Lester W. Clem 



Professor of Immunology and 



Medical Microbiology 



