378 BACTEEIOLOGY OF THE EYE 



It is quite possible that the localizing influence varies for different 

 organisms, and that the circulating poison, as well as the organisms 

 themselves, may have a special affinity for special organs, and be able 

 to find receptors there. A striking example of the fact that the kind 

 of bacteria and the special affinities, unknown to us in detail, play a 

 part is shown by the fact that the preference of the retina previously 

 discussed, does not exist for endogenous infection of the eye with 

 tuberculosis. 



Isolated tubercle of the retina is extremely rare ; tubercle of the uvea, 

 on the other hand, is quite common. The tubercles can only be due to 

 ' affinities,' for the free anastomoses of the capillaries of the uvea can 

 offer no specially strong mechanical obstruction to the passage of these 

 bacilli. Often, perhaps, these metastases are not due to an embolic 

 plugging with infected material, but to a retarding of single bacteria, 

 which, from a purely mechanical point of view, could well pass through 

 the lumen, yet are prevented by some special condition or receptor. 



In rabbits no predilection of the vascular part of the retina for 

 circulating organisms could be shown to exist. With Pyocyancus 

 Stock always obtained metastases in the uvea, never in the retina, 

 using pathogenic hefffi (He/a klein, He/a bussc). Stock also obtained 

 in my laboratory spontaneously healing metastatic inflammations in 

 the uvea and in the retina ; this never occurred with tubercle bacilli 

 (K. M.f. A., 1907, ii.). As the hefas have a relatively large diameter, 

 the narrowness of the retinal capillaries may influence their fixation 

 there. Selenkowski and Woyzechowski (vide infra) also speak of retinal 

 metastases ; it is not clear, however, if they were demonstrated micro- 

 scopically. 



Korotkow similarly reports that in his experiments on endogenous 

 wound infections (cf. p. 104) the metastases always occurred in the 

 uvea (Wmtsch, 1903, No. 50; Ann. cVOcul., 1904, cxxxii., p. 152). 

 Perhaps in other animals it would again be different e.g., in cats. 1 



As a rule, metastatic inflammation cannot be produced in rabbits 

 by the subcutaneous injection of the common pyogenic or septic 

 organisms. 2 This must not be taken to mean that by this mode of 

 infection the bacteria cannot pass into the blood and thus reach the 

 eye, for they can pass by way of the subcutaneous tissues just as 



1 The cases of Stoiy and Stevenson belong to this exceptional class. 



2 After subcutaneous injection of Bacillus coli, Pauas obtained metastatic ophthalmia in 

 cases where the eye had previously been contused. Weber (Deutsche Klinik, 1864, X<>. 48) 

 and Marchand (Berl. Klin. Woch., 1903; Marburg Rep., June 3, 1893) obtained metastatic 

 suppuration of the eye by infecting the subcutaneous tissues of cats, especially when 

 capsulated bacilli of the pneumobacillary group were used. 



