70 IMMUNITY IN HEALTH 



rendering it unlikely that they are any body pigment. 

 Shattock (1916) in specimens of human appendices 

 showing pigmentation, suggested that the pigmentation 

 sometimes seen in the lymph follicles was altered blood 

 pigment absorbed from the alimentary canal, but the 

 reasons given above seem to favour the view that they 

 are largely carbon particles. It would be interesting 

 to know w^hether the subepithelial lymph glands of 

 workers in sooty atmospheres show an unusual amount 

 of pigmentation . 



To elucidate the matter a rabbit was fed for three 

 weeks on food containing a large proportion of carbon. 

 Lamp black was mixed with all its food in sufficient 

 proportions to completely blacken it. The rabbit 

 wasted, probably because it ate less of its unnatural- 

 looking food. It was killed with choloroform and the 

 tonsils, Peyer's patches and appendix examined after 

 staining with eosin. The Peyer's patches showed a far 

 greater proportion of brownish-black masses (Fig. 31) 

 than did the Peyer's patches in several other rabbits 

 in the laboratory whose tissues were examined at the 

 same time. Too much value should not be attached 

 to this observation. It was a single experiment, and 

 the amounts of brown pigment seen in other rabbits' 

 Peyer's patches varies considerably. It was not satis- 

 factorily proved that the pigment was carbon. On a 

 subsequent occasion three young rabbits were etherised 

 and in each case the end of the appendix was brought 

 through an abdominal incision and the wound closed. 

 The end of the appendix was then snipped off with 

 scissors and an emulsion of carmine in normal saline 

 syringed into the lumen of the appendix, the end of 

 which was then ligatured. The three rabbits were 

 killed with chloroform respectively 7, 21, and 42 hours 

 after the operation, and paraffin sections prepared. 

 Each showed carmine in the lumen of the appendix. 



