TUBERCLE. 13r> 



morbid product, like so many others, originates in the conjoint 

 vascular and connective-tissue system. Numerous observations 

 have shown, however, that no connective tissue in the organism 

 is so well adapted for the growth of tubercles, as that whicli 

 constitutes the adventitia of the capillary arteries and arterioles 

 (Uebergangsgefasse). If e.g. we examine a tuberculous pia 

 mater, we may readily convince ourselves that the grey nodules 

 follow by preference the finer ramifications of the arteries. On 

 the larger trunks they adhere, either singly or in little groups, 

 forming one-sided protuberances ; on the finer branches, and 

 those vessels which just exceed the capillaries in calibre, they 

 present themselves as spindle-shaped varicosities involving the 

 whole circumference of the vessel (fig. 44). The larger ones 

 exhibit a whitish opacity, beginning at their centre and extending 

 towards the periphery. This opacity is the visible sign of a fatty- 

 granular metamorphosis, of a cheesy transformation, which con- 

 stitutes the normal mode of degeneration to which the grc}' 

 granulation is liable. We assume that it begins in the oldest, 

 the first-formed and most central cells ; so that the chronological 

 order of the changes which the miliary tubercle undergoes,, 

 manifests itself by the formation of concentric zones, the outer- 

 most of which consist of the tubercle-cells themselves, while 

 the inner ones are made up of the products of their cheesy 

 metamorphosis. Granting the truth of this assumption, it follows 

 ex cmitraiio that we must look for the development of the tuber- 

 cular elements at the periphery of the nodules. 



Miliary tubercles on a vessel from the brain. 



In the adventitia of the mintiter cerebral vessels, a number 

 of very pale, flat, circular nuclei, furnished with nucleoli, are 

 disposed at regular intervals. These may be demonstrated as 



