598 
mediate cells which are sometimes difficult to determine although 
in most instances the larger size and clearer appearance of the nucleus 
suffices for their recognition. Their shape is quite irregular. They 
presumably constitute a cyto-reticulum although in section they seem 
to be more or less isolated. The epithelium as a whole is at these places 
thickened, and usually considerably so. Despite the large number 
of small cells within and beneath it, the basement boundary of the 
epithelium is in most instances still clearly recognizable. The struc- 
ture of these tonsillar masses is illustrated by a drawing of a portion 

Hig. 4. 
Fig. 3. Sublingual tonsil. Salamandra atra. Drawing from a vertical section, 
to show the cells in the epithelium, connective tissue, blood-vessels, etc. V. vein. 
Fig. 4. Sublingual Tonsil. Salamandra atra. Photograph, >< 90, to show the 
structure and relations, 
of a sublingual tonsil and photographs of a sublingual and a preglotti- 
deal tonsil, figures 1, 2 and 3. Figure 6 shows a small nest of round 
cells in the epithelium. It is quite possible that through structures 
in the epithelium of this character, a continuous series of gradations 
might be found between definite tonsillar patches on the one extreme 
to the single leucocytes whose presence in the epithelium of the diges- 
tive system has attracted the attention of most who have dealt with 
its histology. 
It will be apparent from the above description of the amphibian 
tonsils that they agree with the tonsils of mammals in the essential 
structural features. If the comparison is a sound one, the small, round 
cells, are essentially lymphocytes, and the region one of their more or 

ee 
