I 



SEA-FISHERIES LABORATORY. 199 



niethyl-blue-eosin, and it is here also that the bacilli are 

 massed together. Some of these darkly-staining parts 

 appear to lie inside small cavities, which are bounded 

 by fine fibrous tissue arranged concentrically, and it is 

 these large masses which appear to shell-out when the 

 superficial part of the nodule is cut away. It is very 

 probable that the cavity shown in the figure is an 

 artificial one, that is, it is produced by the action of the 

 preservative. But in many of the smaller nodular 

 masses there are also indications of the formation of this 

 concentric fibrous tissue, though there may be no space 

 between the bacilli-loaded centres and the fibrous invest- 

 ment. What we see here is doubtless the encapsulation 

 of the tuberculous centres. But there are also many 

 darkly-staining parts of the section evidently densely 

 packed with organisms, and round these there are no 

 traces of capsules : the darkly-staining tissue passes 

 without any discontinuity into the ground tissue of the 

 section. 



Fig. 3, PI. II, represents a small part of one of 

 these smaller tubercular centres as seen under an oil- 

 immersion lens. It will be seen that there are distinct 

 traces of a capsule, in that fibrous tissue is arranged 

 concentrically round the mass. This rather loose 

 capsular tissue, and some relatively coarse fibres, with 

 large and small connective tissue nuclei, are all the 

 histological elements which can easily be recognised. 

 Besides these there are some rather large patches, 

 staining deeply and without much differentiation with 

 methyl-blue-eosin; and in these are some rounded bodies, 

 staining blue, and containing numerous granules, but no 

 evident nuclei. These present a certain resemblance to 

 the " giant-cells " of typical tuberculous lesions, though, 

 of course, it would be hazardous so to identify them. 



