592 Transactions of the Society. 



XX. — A Method of Disintegrating Bacteria and other 



Organic Cells. 



By J. Edwin Barnard, F.B.M.S. 



(Bead May 17, 1911.) 

 Plate XVIII. 



The pathogenic effect of disease-producing micro-organisms is 

 almost entirely due to the poisons or toxins which they secrete. 

 These toxins are of two kinds. A few organisms, of which the 

 diphtheria and tetanus bacilli are examples, form toxins which are 

 excreted into the medium, e.g. broth, in which they are growing, so 

 that by filtration through a porous porcelain filter such as the 

 Pasteur-Chamberland, the organisms can be removed and the toxin 

 is obtained in the filtrate. But the majority of pathogenic micro- 

 organisms do not excrete their toxins, at least to any extent, and 

 the toxins are retained within, or form integral parts of, the cells 

 of the organisms. This is the case with such organisms as typhoid, 

 cholera, plague, glanders, B. coli, streptococci, staphylococci, etc., 

 and considerable difficulty has been experienced in obtaining their 

 toxins for immunization, for the preparation of anti-sera, and for 

 other purposes. 



If the toxin is thus contained in the protoplasmic contents of 

 the living cell, clearly a method of disintegration in which the cell 

 wall is ruptured and the fluid contents are expressed, might meet 

 the necessity of the case. 



Another purpose for which disintegration of the bacterial cells 

 seems eminently desirable, is the investigation of the chemical 

 composition and properties of the bacterial proteins and other cell 

 constituents. 



Experiments were initiated by Macfadyen and Kowland some 

 years since for obtaining the protoplasmic contents of the living 

 cell by mechanical means, and the apparatus here described has 

 been evolved partly as the result of those experiments and more 

 recently in connexion with those which have been carried out at 

 the Bacteriological Laboratory, King's College. 



The chief conditions to be fulfilled in a machine for effi- 

 ciently accomplishing the disintegration of micro-organisms are 

 as follows : — 



1. The grinding should be effected in a manner which is as far 

 as possible frictionless, so that the risk of rise of temperature and 



