HUBRECHT. Pl. U: 
100 101 
sfitOME ER a 
SF 5. cy 
SR te i 
Baars ee DEO, One: 
(sovaus opine af 
Ss: Sn Oo peat ‘e} 
102 103 
104 
Fig. 100. Longitudinal section through the posterior end of the shrew’s 
blastodisk with earliest appearance of posterior amnionfold (after Hubrecht, ‘90). 
co posterior coelom, vz yentral mesoblast, ¢ trophoblast (cf. Fig. 56 and 61). 
— Fig. 101, 102. Two sections through different blastodiks of Tarsius (nes 675 
and 180 Utr. coll.) in the posterior region of the primitive streak (after Hubrecht, 
02). Fig. 102 is in the more posteriorly situated, at the spot where the tailgut 
(Schwanzdarm) and the allantoidean tube @//, here situated ventrally of the for- 
mer and on the point of diverging. The wall of both is actively proliferating 
vascular tissue. Between the lower border of the allantois and the umbilical 
vesicle a complex of yet more actively proliferating cells is present: this conti- 
nues further backward (where allantois and umbilical vesicle have become further 
severed) as a median proliferating raphe on the umbilical vesicle. In Fig. 101 
lateral wings of mesoblast arise from the entoderm. — Fig. 103. Transverse 
section through the hinder end of an early Tarsius embryo with tubular am- 
nion (am) and allantois /a//) in the already strongly vascularized connective 
stalk cs; wv wall of the umbilical vesicle. — Fig. 104. Longitudinal section of 
sparrow with early mesoblast in a stage of about Fig. 105 (after Schauinsland, ’03). 
