368 



BIOLOGICAL EFFECTS OF RADIATION 



Table 2. — Observed and Calculated Titers of B. coli Agglutinin at Various 



Times during Inactivation by Ultra-violet Light * 



After Dreyer and Hanssen (46) 



*The calculated titers are based upon the assumption that the reaction follows the unimolecular 

 reaction isotherm, namely, k = 1/t log [a/(a — x)], where a is the initial titer, a — x the titer at any 

 time, t; and k a constant. 



and it hardly seems probable that they could have obtained values 

 accurate to the third significant figure. Unless this was so, the perfec- 

 tion of the agreement must have been more or less fortuitous. It should 

 be emphasized that this would not invalidate their conclusion that the 



Fig. 



(o- 



Time in Minutes 



3. — The time course of inactivation of typhoid (x^ — — x) and paratyphoid B 

 _o) agglutinins. Ordinates represent titers on a logarithmic scale, and abscissas 



time on an arithmetic scale. If the processes followed the course of unimolecular reactions 

 the curves should be straight lines. (After Heuer, 85.) 



inactivation follows the course of a unimolecular reaction, as was also 

 true for a large group of toxins and ferments studied by them at the same 

 time (see page 345). 



Heuer (85) has also given time curves of agglutinin inactivation by 

 ultra-violet radiation ; he used serum of asses immunized against typhoid, 

 paratyphoid B, and cholera. His results do not accord very closely with 

 what would be expected if the reaction obeyed the unimolecular reaction 

 equation. Figure 3 shows the low degree of agreement; it is redrawn 



