PLATE 1 
EXPLANATION OF FIGURES 
1 Photograph of metanephric anlage of seven-day chick embryo to illustrate 
stage of differentiation at time of grafting. The ureter bud has given off primary 
branches, which in turn have begun dichotomous division to form secondary 
branches. The ureteric branches are capped with a dense mantle of nephro¬ 
genous tissue. 
2 Photograph from section of graft of metanephric anlage after seven 
days’ growth in the allantois. 
3 Photograph from a graft of the metanephric anlage after twenty-four 
hours’ growth in the allantois. A primary ureteric tubule has begun dichotomous 
division forming ureteric tubules of the second order. The ureteric epithelium is 
covered with a continuous mantle of nephrogenous tissue. 
4 Photograph from a graft of the metanephric anlage after two days’ growth 
in the allantois. To illustrate branching of ureteric tubules and splitting of 
nephrogenous tissue. M.S., metanephric sphere; 2', ureteric tubule of second 
order; 2', ureteric tubule of third order; 4', early stage in dichotomous division 
to form ureteric tubule of fourth order. 
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