322 Prof. G. Dreyer and Dr. E. W. A. Walker. 



Table I. — Experiments with Diphtheria Toxin B in Guinea-pig (subcutaneous 



injection). 



Group of Light Animals. 



No. 



No. 

 of experi- 

 ment. 



Weight 

 of animal, 

 in grm. 



Actual dose 

 d, m c.c. 



Dose (D) in 

 relation to 

 surface x 10'. 

 D = d/W°-<". 



No. 

 of hours to 

 death. 



Dose in per 

 cent, of weight, 

 cu. mm. 

 per 100 grm. 



1 



44 



215 



-01400 



2940 



42 



6-51 



2 



43 



230 



"01375 



2745 



64 



5 -99 



3 



42 



255 



-01575 



2920 



40 



6 -19 



4 



45 



235 



01535 



3020 



38 



6-53 



Average 



234 



0-01471 



2906 



46 



6-31 



Table II. — Experiments with Diphtheria Toxin B in Guinea-pig (subcutaneous 



injection). 



Group of Heavy Animals. 



No. 



No. 

 of experi- 

 ment. 



Weight 

 of animal, 

 in grm. 



Actual dose 

 d, in c.c. 



Dose (D) in 

 relation to 

 surface x 10' 

 D = rf/W ' 72 . 



No. 

 of hours to 

 death. 



Dose in per 

 cent, of weight, 

 cu. mm. 

 per 100 grm. 



1 



28 



425 



-02780 



3560 



30 



6-55 



2 



32 



415 



-02715 



3525 



49 



6-54 



3 



31 



435 



-02845 



3580 



30 



6 54 



4 



35 



415 



-02480 



3220 



44 



5 -08 



5 



30 



435 



-02590 



3258 



32 



5-96 



Average 



425 



-02682 



3429 



37 



6 31 



animals of the same species the lighter animals survive for a much longer 

 period than do the heavier. The explanation of this difference in death 

 time is to be sought in a comparison of the doses calculated in relation 

 to the surface. It is then seen that the dose thus calculated is much 

 smaller in the lighter animals than in the heavier group. 



That this is a valid method of calculating dosage follows from the fact that, 

 under ordinary conditions, substances administered as drugs, to act after 

 absorption into the body, must become diluted in proportion to the volume 

 of the blood. They are carried to the tissues of the body through the 

 medium of the plasma in a relative concentration which is determined by 

 the volume of the circulating blood. But the volume of the blood is a 

 function of the body surface. Accordingly, it follows that the concentra- 



