THE direct observation of the site of Gram stain in cells of micro-organisms could not be attempted before the ultra-thin section technique became available. However, to obtain a suitable section, ...

Hans Christian Gram, the inventor of the Gram staining technique, was a pioneering biologist who devised the system of classification which led to as many as 30,000 formally named species of bacteria ...

Gram-positive bacteria show blue or purple after Gram-staining in a laboratory test. They have thick cell walls. Gram-negative bacteria show pink or red on staining and have thin walls. They release ...