NATURE OF THE TOXINE. 367 



preserve its powers little altered for several months, but on 

 the other hand, it gradually loses them when exposed to the 

 action of light and air. Heating at 58 C. for two hours 

 destroys the toxic properties in great part, but not altogether. 

 When, however, the toxine is evaporated to dryness, it has 

 much greater resistance to heat. One striking fact, 

 discovered by Roux and Yersin, is that after an organic 

 acid, such as tartaric acid, is added to the toxine the toxic 

 property disappears, but that it can be in great part restored 

 by again making the fluid alkaline. 



The toxic body in filtered cultures can be precipitated 

 by alcohol, and is also carried down by calcium phosphate. 

 It is, however, soluble in water and dialyses somewhat 

 slowly through animal membranes. By repeated precipita- 

 tion and again dissolving, aided by dialysis, a solution is 

 obtained which, on evaporating to dryness, gives a whitish 

 yellow powder containing the toxic body, though not in a 

 chemically pure condition. From the characters described 

 Roux and Yersin considered that it belonged to the group 

 of diastases or enzymes. 



The true chemical nature of the diphtheria toxine is 

 still unknown, and the matter is further complicated by the 

 possibility that if a ferment is formed by the bacilli it 

 may produce other toxic bodies of a non-diastatic nature. 

 Guinochet showed that toxine was also formed from the 

 bacilli when grown in urine with no proteid bodies present. 

 After growth had taken place he could not detect proteid 

 bodies in the fluid, but on account of the very minute 

 amount of toxine present, their absence could not be 

 excluded. Uschinsky also found that toxic bodies were 

 produced by diphtheria bacilli when grown in a proteid-free 

 medium. 1 It follows from this that if the true toxine is a 

 proteid, it may be formed by synthesis within the bodies of 

 the bacilli, as well as by a change in the proteids of the 



1 Uschinsky's medium has the following composition : water, 1000 

 parts; glycerine, 30-40; sodium chloride, 5-7; calcium chloride, .1; 

 magnesium sulphate, .2-. 4; di-potassium phosphate, .2-. 25 ; ammonium 

 lactate, 6-7 ; sodium asparaginate, 3-4. 



