X. TMV STUDIES IN GENETIC CODING 



481 



Fig. 2. Electron micrograph of TMV obtaiued by new technique of staining 

 with phosphotungstate. The longest straight rod in the picture is 0.45 /i long, 50% 

 longer than the typical length of RNA containing virus rods. The helical stacking 

 of subunits and the central channel, here outlined by a coat of contrasting phos- 

 photungstate solution, are clearly visible. 



