DIAGNOSIS OF TUBERCULOSIS 485 
bacilli from four to five weeks previously by the subcutaneous route. 
Intracerebral inoculation of tuberculin will kill tuberculous guinea- 
pigs in much smaller amounts. Postmortem there is intense conges- 
tion around the tuberculous foci and ecchymotic hemorrhages in the 
viscera. Twenty-five hundredths (0.25) of a cubic centimeter of 
old tuberculin woukl be extremely dangerous to inject into a tuber- 
culous man. It would probably result fatally.^ 
3. The Principle Involved.— The reaction obtained in tuberculous 
man or animals by the injection of tuberculin or other products of 
the tubercle bacillus depends upon the fact that the tuberculous 
subject is sensitized to the proteins of the tubercle bacillus as the 
result of infection with this organism.- The presence of the proteins 
of the tubercle bacillus and perhaps other products of growth of the 
tubercle bacillus stimulates certain body cells of the host to produce 
specific proteolytic ferments which dissolve these proteins M'ithin the 
body.^ When tuberculin is introduced into the tuberculous host these 
specific proteolytic ferments liberate from the tuberculin a poisonous 
cleavage profluct which has three specific effects: a focal efi'ect, char- 
acterized by intense irritation and inflammation around the tuber- 
culous foci, a local effect, and a general efl'ect which is characterized 
by a rise of temperature and other general systemic reactions. The 
tuberculin reaction is an anaphylactic reaction according to Vaughan 
and Baldwin.'* 
4. Technique of the Tuberculin Reaction.^— The tuberculin reaction 
elicited in man by the introduction of tuberculin is of two types, 
depending upon the method of injection employed. If introduced 
subcutaneously so that the tuberculin enters the lymph or blood 
streams, even in minute amounts, the reactions consist of three rather 
distinct phases: a general, a local, and a focal reaction respectively. 
If, on the contrary, the injection is purely superficial in the epidermis 
or on the conjunctiva the reaction is almost exclusively local. 
(a) The Subcutaneous Reaction (Koch). ^The characteristic response 
following the subcutaneous injection of appropriate amounts of old 
tuberculin is a generalized reaction consisting of a rise in temperature 
of at least one-half a degree above the highest temperature exhibited 
before the inoculation. This rise in temperature usually begins twelve 
to eighteen hours after the injection; it may be delayed to twenty- 
1 Deist (Beitr. z. Klin. d. Tuberkulose, 1912, 23, 547) has observed albumoses in 
the urine of tuberculous patients following the injection of tuberculin. 
2 For discussion of theories of the tuberculin reaction, see Kuthy and Wolff-Eisner 
(Die Prognosenstellung bei den Lungentuberkulose, Berlin and Vienna, 1914). 
3 White (Jour. Med. Res., 1914, 30, 393) has shown that lipoids of the tubercle bacillus 
neither sensitize nor induce anaphylaxis in experimental animals. 
* Protein Split Products, Philadelphia, 1913. See Baldwin (Yale Med. Jour., Feb- 
ruary, 1909) and Studies from the Saranac Laboratory for the Study of Tuberculosis. 
1904-1910) for excellent summaries. 
* The diagnostic and particularly the therapeutic use of tuberculin requires much 
skill and experience. For details, see Baldwin and Brown (Osier's Modern Medicine, 
1925, vol. 1, Chapters IV and VI.) 
