1. Intact bacteria probably resist tryptic digestion because of the absence of an exposed protein substrate.
2. Dried organisms resist digestion in a degree proportional to their content of unsaturated lipoids.
3. Lipoidal extractives reduce the resistance to tryptic digestion.
4. The extracted lipoids (saponified) are antitryptic in a degree proportional to their unsaturation.
5. The inactivation of the antiferment in Gram-negative organisms is probably due to changes in the degree of lipoidal dispersion.
6. Bacteria adsorb lipoids from the serum when incubated at 37° C. Such organisms when dried are found to be more resistant to tryptic digestion than untreated organisms.