Abstract
The Gotschlich procedure for the production of carbohydrate antigens from the supernatant fluids of cultures of Neisseria meningitidis groups A and C was modified. Steps involving digestion with nucleases and gel filtration through Sephadex G-50 were added, the number of extractions was greatly reduced, and high-speed centrifugations were eliminated. The antigens thus obtained appeared to be entirely comparable to those described by Gotschlich et al. in physical, chemical, and antigenic properties. A slight degree of protection of mice was repeatedly demonstrated with extraordinarily large doses of antigen (50 mug/mouse), but not with smaller doses. Toxicity of the antigens for laboratory animals was very slight.