The Bacillus tuberculosis. 



127 



addition, some constant and quite remarkable facts, namely, a well- 

 defined difference in the anatomy of the connective tissue between 

 scrofulous and non-scrofulous animals. 



To the scrofulous class belong unquestionably the tame rabbit 

 and guinea-pig and all animals in close confinement, while to the non- 

 scrofulous belong the cat, dog, and animals at large. 



I have here two specimens under the microscope, to which I in- 

 vite your particular attention, as they illustrate the histological 

 difference referred to between the normal tissue of the rabbit and that 

 of the cat. The animals, which are representatives of the scrofulous 

 and non-scrofulous species, were of equal age, both healthy, killed in 

 a similar manner, and the sections, which were taken from precisely 

 corresponding parts, are equally treated and mounted. I selected in 

 this case the corresponding parts of the nose of the two animals. It 

 makes, however, no difference what part of the body is taken, as long 

 as it shows some connective tissue. The relative difference to be 

 spoken of is equally striking everywhere in the two animals in corre- 

 sponding parts of the body. At the first glance it is seen in the 

 specimen from the rabbit that there are a great many more cells in 

 the microscopic field than in the corresponding field in the specimen 

 from the cat; again, that the cells which are located in both cases 

 between the interstices of the connective tissue are predominately 

 round and crowded in the rabbit, with only a few spindle-shaped and 

 stellate cells, while in the cat the cells are mainly of the last two 

 varieties, scattered and few in number. In other respects the con- 

 nective tissue proper appears similar in both cases. 



The difference seen in the tissue of the rabbit and the cat exactly 

 correspondents to a similar difference between the scrofulous human 

 being on the one hand and a normal individual on the other. Re- 

 peated microscopic examinations of well-selected cases have shown this. 



Let us see now what those cells seen in the connective tissue of 

 the specimens under the microscope signify. 



their scrofulous tendency. It is possible that this surplus of lymphatic structure and 

 of the lymphoid cells comprising them plays an important rôle in furnishing the 

 elements for the tubercle." 



