40 A MANUAL OF BACTERIOLOGY 



Wells, C/nniinil J'al/toluijy, 11)07; Jlcwlell, Ail. " Toxinfl and 

 Antiloxins," Thorpe's Diet, of Chemistry, 1J)I.*{. Kor Cicncial 

 Bibliography, HOC Kollo and Wassci maim, ratkuycntn J\l ikroor- 

 yaniarncn. 



Endotoxins 



The majority of pathogenic micro -organisms do not excrete any 

 appreciable amount of toxin ; the toxin remains within the cells. 

 To such an intra-cellular toxin the. name ol' " endotoxin " has been 

 given. The toxins of the staphylococci and streptococci, UK- 

 typhoid-colon group, plague, cholera, etc., arc cndotoxins. Various 

 methods have been employed to prepare these endotoxins, such as 

 extraction of the cells by the action of weak alkalies and enzymes, 

 and by autolysis or self-digestion. 



The late l)r. Allan Maefadyen conceived that if the infra- 

 oellular toxins (endotoxins) of such organisms us the typhoid 

 bacillus, cholera vibrio, etc., could bo obtained free 1'rom the 

 bacterial cells, it might be possible to prepare sera (anti-endoto.xic 

 sera) of much more therapeutic potency than the ordinary anti- 

 microbic sera. 



The disintegration of the bacterial cells in the presence of intense 

 cold, to prevent chemical change in the bacterial juice obtained, 

 was the method devised by J^lacfadyen to atla.in (Ins end. With 

 the aid of his colleagues, Mr. Rowland and Mr. Barnard, and ol his 

 laboratory assistants, Messrs. Burgess and Thompson, apparatus 

 and methods were evolved to ollect this. 



By growing on the surface of agar or other suitable medium in 

 plate bottles (Fig. 16), scraping oil the growth and suspending this 

 in salt solution, ccntrifugalising at high speed, and collecting the 

 bacterial cell-mass on the walls of the centrifuge vessels, suilicient 

 material is readily obtained to grind or triturate, and thus dis- 

 integrate the bacterial cells so as to liberate their contents. This 

 is accomplished by means of a special machine, the essential part ol 

 which consists of a metal cone revolving at a high speed in a metal 

 pot, the bottom of which is shaped so as to lit the cone. The pot, 

 with its contents, is immersed in a vessel of liquid air or other 

 freezing mixture, and the bacterial mass is ground. 



After grinding, the ground material is made up with distilled 

 water or with 0*1 per cent, sodium hydrate, so as to form a 10 per 

 cent, solution (calculated on the original weight of the moist 

 bacterial paste); this is centrifugalised, and the lluid is liltend 

 through a sterile Berkefeld lilt rr. 



