Ou, L.-T., and R. E. MARQUIS. 1972. Coccal cell-wall compactness and the swelling action of denaturants. Can. J. Microbiol. 18: 623-629. Isolated cell walls of Micrococcla lysodeiktic~rs and Stap/tylococc~ts nrirel~s were found to have relatively low densities in both the dried and hydrated states. Thus, it appears that the component polymers of these structures do not form cr)stallites or other highly condensed assemblies, but rather, that their dislribution within the wall matrix is similar to that of the polymer chains in low-density, ion-exchange resins. Micrococclts lysodeikticlu walls, which are conlposed mainly of peptidoglycan, swelled significantly when they were heated or transferred to 8 M urea solution. This finding suggests that the compactness of walls and their component peptidoglycans is determined in part by weak interactions that can be disrupted by urea o r by heat.Ou, L.-T., et R. E. MARQUIS. 1972. Coccal cell-wall compactness and the swelling action of denaturants.Can. J. Microbiol. 18: 623-629. On a observt que les parois cellulaires isoltes de &Iicrococcris lysodeikticus et Stnp/rylococcus allreus ont de faibles densitts relatives, tant a l'etat sec qu'a l'ttat hydrate. I1 semble que les polymtres qui composent ces structures ne ferment pas de cristaux ou d'autres assemblages grandement condenses, mais que leur distribution dans la matrice de la paroi est semblable a celle des chafnes de polymires a faible densitC, i.e., les rtsines tchangeuses d'ions. Les parois de M . lysodeiktic~ts, lesquelles se composent principalement de peptidoglycans, renflent considtrable~nent lorsqu'elles sont chaufftes ou qu'elles sont transfertes dans une solution d'urte 8 M . Cette observation suggire que la cornpaticite des parois et de leur peptidoglycans est determinte en partie par des interactions faibles, ces derniires peuvent &tre rtduites par l'uree ou par la chaleur.