349 



In many cases the characteristic histology is more important than 

 any bacteriological test which can be made. When the other methods 

 fail, we must insist on the presence of the typical tubercle, and not 

 accept as such a few epithelioid and giant cells. 



A necrosis at the centre is especially important ; slight degrees are 

 sufficient for a diagnosis. 



There is a form of chronic tuberculosis of the conjunctiva and the 

 lacrymal sac, in which the picture is not typical, though the tubercle 

 bacilli can be found by the inoculation test. Such cases clinically 

 present great difficulties in diagnosis ; they were described by Wertz, 1 

 and Sulzer 2 (lacrymal sac). 

 Stock 3 found atypical appear- 

 ances in many stages of intra- 

 ocular tuberculosis of the 

 uvea, not only in rabbits, but 

 also in the human eye. 



The introduction of a pure 

 culture of the Bacillus tuber- 

 culosis into the anterior 

 chamber, provided that the 

 strain is pathogenic for the 



^jfr"- 't 



animal used, produces a 

 caseating inflammation, 

 which passes on to liquefac- 

 tion and perforation. It is 



only when minute quantities , 



are introduced that the ap- 

 pearance is that of a tuber- FIG. 76. TUBERCLE BACILLI IN SECTION.* 

 cular iritis. This inoculated 



tuberculosis of the iris, with its local and general results, is often 

 used for the determination of the tubercular reaction (Baumgarten, 

 Zimmermann, and later by von Hippel and Schiek). 



According to the experiments of Haensel, Panas, Bach, 5 Greef and 

 Nakagawa, 6 tubercle bacilli in the cornea produce only slight and 

 transient changes. It is interesting to determine which elements 

 commence the formation of the corneal tubercles. The fixed corneal 

 corpuscles are first affected (Marchand and Goecke, ' Experiments on 



1 K. M.f. A., April, 1907, i. - Soc. d'Ophth. de Paris, February, 1907. 



3 K. M.f. A., 1907, Beilageheft, and A.f. 0., 1907. 



4 Cornet and Meyer, 'Kolle imd Wassermann, ' 1903, ii. 121, 

 3 A.f. A., 1896, Bd. xxxii. 



6 A.f. A., 1903, Bd. xlix., S. 191 (the literature is there). 



'** 



