ENZYMIC DEGRADATION AND BIOSYNTHESIS 



75 



Fig. 17. Effects of penicillin on cell-wall structure, (a) Thin section 

 of untreated cells of Staphylococcus aureus (x 36,000); (b) effects of ex- 

 posing Staphylococcus aureus to penicillin for three hours (x41,500). 

 From the study of Murray, Francombe, and Mayall (Ref. 57). (c) 

 Vibrio metchnikovi "protoplasts" prepared by growth in the presence 

 of penicillin. The weakened wall from the right-hand "protoplast" 

 became detached during preparation for electron microscopy (x 12,500). 

 M. R. J. Salton, unpublished. 



Since the early investigations of Park and Johnson -^ and 

 Park,29 a number of uridine nucleotides containing typical 

 wall components has been isolated from untreated cells as 

 well as from organisms whose giowth has been inhibited by 

 antibiotics or deprivation of specific amino acids. Baddiley 

 et al.*^^ isolated cytidine diphosphoribitol and cytidine di- 



