THE RABBIT'S APPENDIX 53 



a rounded portion of one of the superficial layer of 

 lymphoid nodules. The projecting portion of the lym- 

 phoid nodule also is covered by the columnar epi- 

 thelium of the calyx-gland, but so many small glandular 

 lymphocytes may be seen amidst the columnar cells 

 that in some places this layer may almost appear to 

 be wanting. Many of the glandular lymphocytes are 

 crowded with bacteria. 



The superficial lymphoid nodules which project into 

 the calyx-glands contain principally small glandular 

 lymphocytes. Many of these evince their phagocytic 

 ability by the number of ingested bacteria they display. 



Beneath the superficial lies a deeper layer of lym- 

 phoid nodules. These nodules are much larger in size. 

 Small and large glandular lymphocytes occur and in 

 addition giant cells, the last two kinds being especially 

 crammed with bacteria and carbon particles. Situated 

 basally, near to the periphery of each deeper nodule, 

 may be seen irregular masses which do not take any 

 stains. These are brownish in colour and contain 

 darker particles. These probably represent the indi- 

 gestible debris from the omnivorous phagocytic activity, 

 either lying in an efferent lymphatic space or deposited 

 more permanently in some interstices of the gland. 

 I have often traced intermediate appearances 

 between the giant-cell and these inert masses. Some- 

 times these masses are so large as to be visible t'o the 

 naked eye, presenting those dotted rings on the serous 

 aspect to which allusion has already been made.* 



It is perhaps not unfair to compare the superficial 

 layer of lymphoid nodules of the rabbit's appendix 

 with the cortex of an interstitial lymphatic gland ; and 

 the deep layer of nodules with the medulla of an inter- 

 stitial lymphatic gland. 



* Similar patches of pigment have been described by Professor 

 Shattock (1916) in the human appendix. 



