HUBRECHT. Pl W. 
a 
e cata pe Apidae 
: SKS GOAL ae 
aT i ee 
Pe ha ee 
E WC 
oe Uns orbaicarlgth! 149 
é yg ei 3 fe 
GOI bp 
NIA, 
Fig. 110. Longitudinal section of a sparrow’s blastodisk (after Schauins- 
land, 03). ff protochordal plate, cz notochord, vm ventral mesoblast. — Fig. 111. 
Longitudinal section of an early embryo of Chamaeleo (after Schauinsland, 03). 
pp protochordal plate, pw protochordal wedge, vm ventral mesoblast, 7c neuren- 
teric canal, @ amnion, / two-layered trophoblast. — Fig. 112 to 114. Three 
sections through early blastodisks of Sphenodon (after Schauinsland, 03). In 
Fig. 114 (longitudinal section) protochordal plate (Af), protochordal wedge pw, 
ventral mesoblast (vz) and trophoblast ¢- are indicated. In this phase of noto- 
genesis a long and distinct neurenteric canal (cv) is present. In Fig. 112, which 
is further anteriorly situated than Fig. 113, the protochordal plate ff is transver- 
sely cut, as well as the annular zone of proliferating entoderm az spreading 
backwards and contributing to the formation of the area vasculosa. In lig. 113 
the notochord chk has commenced its mediolongitudinal differentiation. 
