152 HUGH GLASGOW* 



There appears to be little question that the normal intestinal 

 bacteria of higher animals, such as the groups represented by 

 Bacillus coli, Bacillus (lactis) aerogenes, and Bacillus bifidus, do 

 possess definite antagonistic properties for the less perfectly 

 adapted species, although the exact mechanism of this antagonism 

 has been explained in a number of different ways. Some would 

 account for this phenomenon as being due largely to over- 

 crowding, with consequent starvation of the idss hardy species. 

 The normal forms being constantly present in the intestine in 

 large numbers, and well adapted to vigorous growth in certain 

 well-defined regions, would naturally be better able to appropriate 

 any nutrient materials which had escaped resorption by the host 

 than those forms which only occasionally invade the intestine. 



The various products of fermentation produced by these 

 bacteria, especially the organic acids, are also held to be of very 

 great importance in this same connection. 



Another and apparently an exceedingly important factor in 

 this antagonism lies in the production by these organisms of 

 definite toxin-like bodies, the "autotoxins" of Conradi and 

 Kurpjuweit, which in some way clearly exert a restraining in- 

 fluence upon the development of many bacterial species. 



These latter substances, which have been carefully studied 

 especially for Bacillus coli, by Eijkman, as well as by Conradi 

 and Kurpjuweit and others, are regarded by these authors as 

 mainly responsible for the familiar weakening and ultimate death 

 of bacteria in old cultures which was formerly held to be due 

 chiefly to a gradual exhaustion of the nutrient materials, resulting 

 in death by starvation. 



It was found by Eijkman, and later by Conradi and Kurpju- 

 weit, that such an old and apparently exhausted culture could 

 again be made to support growth by inactivating the toxins, as 

 by heating to 60 C. or by filtering through porcelain, and that 

 these same toxins were constantly present in normal feces, 

 where they could be detected in very high dilutions, even as 

 great as 1-10,000. 



These "autotoxins," as the name implies, affect the organism 

 producing them as well as various other species, although, as is 

 suggested by Conradi and Kurpjuweit, under normal Conditions 



