HUBRECHT. 
105 
Pl. V. 
106 
Fig. 105 to 109. Five surface 
views of the early aspect of the sparrow’s 
blastodisk (after Schauinsland, 03). In 
Fig. 105 there is as yet only an ento- 
dermal protochordal plate pf (ef. longi- 
tudinal section of Fig. 104); in Fig. 106 
a downwards growing protochordal wedge 
pw begins its fusion with the protochor- 
dal plate; in Fig. 107 mesoblast has 
grown out from the borders of the elon- 
gated dorsal mouth; in Fig. 10S the ven- 
tral mesoblast vz has made its appea- 
rance; in Fig. 109 the sickle-shape be- 
comes visible in the posterior mesoblast. 
nch notochord. 
