METANEPHRIC ANLAGE OF CHICK 
425 
3. Growth oj the stroma. During the early stages of growth 
in the allantois, the loose mesenchyme of the anlage develops 
a high degree of vascularization. The development of the vessels 
was leadily followed out. At the periphery of the anlage and 
later throughout its stroma spaces separating groups of individual 
cells are seen to appear. These spaces are apparently distended 
with fluid. The mesenchymal lining of the spaces, at first irreg¬ 
ular in its outline, soon acquires the character of typical endo- 
N.T. 
Ms. 
Text figure D Camera-lucida drawing to illustrate granulopoiesis and seg¬ 
ments of urinary tubules. Metanephric graft of six days’ growth, c., capillary; 
Gbl., granuloblast; Hbl., hemoblastjxlf.jB., Malpighian body; Ms.c., mesenchymal 
cell; N.T., secretory tubules; U.T., collecting tubule. 
thelium. The spaces establish communications with one 
another, forming in this way a vascular net, which soon estab¬ 
lishes connections with the allantoic vascular channels. Figure 
7 illustrates the high degree of vascularization which develops 
in grafts of the metanephric anlage. Broad vascular channels 
encircle the organ and traverse the spaces separating its various 
lobes. Smaller vessels and capillaries are numerous between 
the lobules and among the nephric tubules. 
