ioi8 



TUBERCULIN AND THE TUBERCULIN REACTION 



The intracutaneous test is by far the most accurate. Therapeutic administration has 

 been carried out also by inhalation, ingestion, and even absorption through the 

 rectum, urethra, and vagina — methods uncertain, unnecessary, and with no advan- 

 tages to recommend them. The details concerning these tests may be read in Cal- 

 mette's book.' 



OLD TUBERCULIN 

 BFKECT OEE MONTH APTEP INOCULATION 



O.COOI Cc^ 



0.00001 Cc 



Fig. I. — Old Tuberculin in increasing dilution was injected into the left testis in a series of 

 tuberculous guinea pigs, the fluid volume injected being o.i cc. in each case. The animals were killed 

 one month later. In each case the right, control, testis was found to be normal. The illustration 

 shows the condition of the left testis into which injections were made. There is profound atrophy of 

 the tubules of the testes receiving injections with o.oi cc, o.ooi cc, and o.oooi cc. Spermatocytes, 

 spermatids, and spermatozoa have disappeared. Practically no effect is visible at o.ooooi cc, although 

 the tubules in this case were found to be somewhat smaller than in the right testis into which no 

 injections had been made. The smallest amount causing complete abolition of spermatogenesis was 

 thus O.OOOI cc. On the arbitrary scale here developed this represents i spermatocyte unit, and this 

 sample of tuberculin therefore contains 10,000 spermatocyte units per cubic centimeter. 



the chemical nature of tuberculin 

 koch's original investigations and views 

 Robert Koch believed, with scarcely questionable correctness, that a chemically 

 as well as biologically specific active principle was responsible for the tuberculin ac- 



' Calmette, A.: Tubercle Bacillus Infection and Tuberculosis in Alan and Animals (trans, by 

 Soper and Smith). Baltimore, 1923. 



