DESCRIPTION OF FIGURES 
All the drawings have been made with a1.5-mm. Zeiss apochromatie objective, 
no. 10 Spencer ocular and camera lucida, and are reproduced without reduction. 
PLATE 1 
EXPLANATION OF FIGURES 
1 Group of follicular cells showing the usual form and position of the reticu- 
lar material from a preparation made by Cajal’s uranium and silver nitrate 
method, which blackens it. 
2 Follicular cells prepared by Da Fano’s cobalt nitrate silver method. At 
(A) one large cell presents an apparent reversal in polarity, since the blackened 
reticular material is on the opposite side of the nucleus remote from the follicular 
cavity. 
3 <A row of cells in all of which the position of the reticular material is re- 
versed, from a preparation made by the same method. 
4 Follicular cells showing different degrees of reversal in position as one 
passes from left to right, from another guinea-pig treated by the same method. 
5 Follicular cells fixed in Zenker’s fluid and stained with iron hematoxylin, 
showing a system of clear canals in the same position as the blackened material 
illustrated in figure 1. 
6 Cells prepared by Da Fano’s cobalt nitrate silver method, showing reticu- 
lar material which has moved up unusually close to the follicular cavity and which 
exhibits vesicle-like enlargements. Compare this with its average position and 
form illustrated in figure 1. 
7 The same, without the swellings. 
8 Three layers of epithelial cells bordering the follicular lumen and showing 
no sign of polarity as indicated by the variable location of the blackened reticular 
material, same method. 
