PLATE 3 
EXPLANATION OF FIGURES 
Oil-immersion objective and no. 4 ocular (Leitz) except fig. 8 which was made 
with the high-dry lens (no. 7, Leitz) and fig. 10 which was made with the low- 
power objective and no. 2 ocular (Leitz). 
8 Carbon-containing endothelial cells lining a dilated lymph-vessel in the 
subcutaneous tissue ten days after first subcutaneous injection (dog 152, 
table 2). 
9 Carbon-containing phagocytic mononuclear leucocyte and one containing 
a polymorphonuclear leucocyte in the peripheral sinus of a retroperitoneal 
lymph node one day after subcutaneous injection (dog 177, table 2). 
10 Lymph nodule from a retroperitoneal lymph node ten days after subcu- 
taneous injection (dog 152, table 2). Most of the carbon is in phagocytic mono- 
nuclear leucoctyes in and near the sinuses. 
11 Blood-vessel at the periphery of a germinal center (retroperitoneal lymph 
node, dog 151, table 1). The endothelial lining shows carbon. <A mitotic figure 
and two large lymphoblasts at the right of the vessel. 
