In arranging the symposium on microbial precise information supporting this belief has toxins, an attempt was made to stress those been obtained in studies of dysentery bacilli, aspects in this general field which have not been the Shiga bacillus by British workers, and the discussed frequently. It is for this reason that Flexner bacillus by Goebel in this country. Less emphasis was placed on the so-called endodefinite information concerning the endotoxins toxins, and such varied topics as rickettsial and of microorganisms such as the cholera vibrio, phytopathogenic toxins were included. To avoid Bruceila spp., a number of species of enteric omission of the rather well known and often bacilli, and certain of the gram-negative cocci is discussed exotoxins, Dr. W. E. van Heyningen in essential agreement. Dr. Burrows indicated was asked to cover some aspects dealing with further that some evidence exists that suggests these as well. that the cell substance of the toxic bacteria conThe discussions were divided roughly into two tains more than one species of toxicity, but it is parts. Dr. Burrows and Dr. Stetson covered possible, or even probable, that this is an artisome phases of the recent work on endotoxins, fact. Of the components of endotoxin as it exists which was followed by a discussion led by Dr. in the cell, it would appear that the protein is Cromartie. Following this, plague, rickettsial, irrelevant to toxicity and possibly to antigenand phytopathogenic toxins were discussed, and icity and occurs in loose combination, since Dr. van Heyningen gave his report. yields of apparently intact endotoxin may be Dr. Burrows stressed the fact that bacterial increased as much as twofold by preliminary endotoidns are of substantially the same nature, digestion with proteolytic enzymes. It is also regardless of origin, and that they consist of a obvious, the speaker indicated, that the lipid substance of relatively low molecular weight component is unrelated to toxicity and antiwhich occurs in combination with protein and genicity. The polypeptide fraction, however, appolypeptide, polysaccharide, and lipid. The most pears to be essential to complete antigenicity ' Symposium held at the Fifty-fifth General and the polysaccharide may function as a Meeting of the Society of American Bacteriologists hapten, but the low molecular weight component at New York City, May 12, 1955. has not been prepared in active form except in 2 Convenor. combination with one or another of these sub-