TUBERCULIN THERAPY 197 



consists of the extract from 1.0 milligramme of tuber- 

 cle bacilli; with Tuberculinum Purum or " T. P.," 

 the usual primary dose is 0.02 milligramme. In the 

 absence of reactions, the size of these doses is doubled, 

 semi-weekly and later weekly, until the maximum 

 tolerant dose is reached. Dixon advises that the mini- 

 mal dose be repeated five times at intervals of five days, 

 before proceeding to the next higher dose, which is 

 ten times the strength of the first. This is repeated 

 five times before giving dilution No. 3, which is twice 

 the strength of the former. Thus the patient is car- 

 ried through seventeen more dilutions, each being an 

 increase of one-tenth of its predecessor. In children 

 the size of the dose is regulated by the age of the 

 patient, as in any other therapeutic remedy. As a rule 

 children tolerate tuberculin very well. 



For most tuberculins the technic of making dilu- 

 tions as described in the previous chapter on page 172 

 will prove satisfactory. Pharmaceutical firms now 

 prepare various tuberculins in serial dilutions, bearing 

 legends explanatory of their use, and rendering their 

 employment a matter of great convenience. If the 

 dilutions are not freshly prepared, caution must be 

 exercised to see that they are not clouded or precipi- 

 tated, hence inert, due to the action of the preservative 

 phenol. Tuberculins for subcutaneous inoculation are 

 thus marketed in vials with hermetically sealed rubber 



