[nicholls] blood sera IN TUBERCULOUS INFECTION 21 



fact that the toxins and extracts of the tubercle bacillus used for immu- 

 nizing purposes have been obtained by heat or by various' chemical pro- 

 cesses so that they do not represent the full toxic properties of the 

 bacillus. To obviate this objection Koch's new tuberculin (Bacillen- 

 emulsion) was employed. Perhaps a word or two of explanation as to 

 the nature of this substance may not be out of place at this juncture. 



Koch takes a definite weight of tubercle bacilli, filters them from 

 all culture fluid, grinds them up with two hundred parts of 1/50 nor- 

 mal soda solution, and then centrifugalizes. He then pours off the 

 supernatant fluid, adds weak acid to the residue until only slightly alka- 

 line, and finally dilutes with a standard weak solution of carbolic acid 

 and salt to the extent of one to three thousand. Glycerine is also add- 

 ed, and the final emulsion represents five milligrammes of pulverized 

 bacilli in every cubic centimetre. (Deutsche med. Woch., Nov. 28, 

 1901). The injection of this into tuberculous persons' brings about a rise 

 of temperature of one and a half to two degrees centigrade. The dose 

 of the first injection is 0.0025 milligramme rapidly increased two or 

 five-fold until the reaction appears. 



To obtain convenient amounts for injection, the bacillus emulsion 

 was' diluted according to Koch's directions with a standard diluting 

 solution containing 0.8% sodium chloride and 0.5% carbolic acid. 



Three strong healthy goats were subjected to the injection of the 

 bacillus emulsion in gradually increasing amounts, the whole procedure 

 extending over about seven months. The reason for spreading the 

 injections over so long a period is that it had been found by Marag- 

 liano and others that the animals stand it better and the results are 

 more satisfactory. It was determined beforehand by culture experi- 

 ments that the emulsion was sterile. The injections were given subcu- 

 taneously in the neck under strictly aseptic conditions once a week 

 until towards the end of the allotted period. Previously, however, the 

 normal temperature for the goat was ascertained. The amount of the 

 emulsion injected was at first .0025 milligrammes repeated once a week 

 for three weeks and cautiously increased until at the end of three 

 months the goats were receiving 0.015 milligrammes'. Subsequently the 

 amount injected was doubled each week, until at the end of seven 

 months 15 milligrammes was reached. After the first three months also 

 the temperature before inoculation was taken as well as afterwards, 

 twice in the following twenty-four hours. The normal temperature of 

 the goat varies between 101 and 103 degrees Fahrenheit. In only one 

 case did the injection (of 10 mmg.), cause a rise of temperature from 

 ]02° to 103° and 3-5ths, but this was only 3-5ths of a degree above the 

 maximum normal variation. The subsequent injection was lessened to 

 7.5 mmgs., and then again increased. During the last few weeks while 



