600 
away from the tonsils revealed the fact that they generally contain an 
unusual number of lymphocytes, as is indicated by the photographs 
reproduced as figures 7 and 8 and the drawing, figure 9. 
Within the tonsils themselves the vascular (venous) radicles 
are often completely gorged with these cells so that they are differen- 
tiated from the surrounding tissue only with difficulty. While this 
latter fact might be interpreted as due to a collection of lymphocytes 
from without, this seems hardly likely under the conditions. The 
round cells do not seem to leave the tonsils by means of lymphatic 
but by venous channels. Although the sublingual tonsil in the toad 
is directly above a lymphatic sinus (ceratohyal sinus) only an occasional 
lymphocyte is found therein. 
Mitotic figures occur with fair frequency indicating that cell- 
proliferation is going on though not with marked rapidity. In the 
86 mm specimen in the 
preglottideal tonsil, nearly 
every section contains in the 
tonsil a mitotic figure as 
many as four being found oc- 
casionally in a single section. 
Development. Because 
of the relatively late devel- 
opment of these structures, 
it is rather difficult to as- 
certain the morphological 

Fig. 9. Outline drawing to show the { 
lingual vein in its relation to the sublingual transformations that precede 
tonsil, in the toad, and the relatively large their appearance and which 
number of lymphocytes in the veins entering : 
from the tonsil. A few cells of those composing May be connected therewith. 
the tonsil are figured outside the vein. >< 250. In fact in the case of the 
smaller tonsillar areas (I, II, 
V, VII, IX, XII) which have been spoken of as less constant in 
location and occurrence, the question of their morphogenetie cor- 
relations has not even been considered. While the developmental 
relations of the choanal tonsil (VIII) might undoubtedly have been 
determined, attention has in the present study been limited to the 
three most constant, namely, the preglottideal, lateral and sublingual 
tonsils (IV, III; VI). | 
As has been previously stated, there is no trace of these structures 
in the larvae, nor indeed do they appear until transformation is fully 

ae An A An re er 
