THE HUMAN EMBRYO AT DIFFERENT PERIODS. 



77 



R 100. SIDE VIEW OF AN EMBRYO, measuring about 

 5 > mm. from the root of the neck to the. base of the tail, 

 I ,nd about 47 mm. from the crown or mid-brain region 

 I ,o the base of the tail, that is to the breech or rump. 

 I From Keibel and Elze's Normdttafeln.) The neural 

 I ube is closed. The limb buds are quite distinct, and 

 1 he maxillary process of the mandibular bar has grown 

 I orward below the eye (dorsal to the eye in the Fig.). 



FIG. 101. EMBRYO OF 7 '2 MM., CR MEASUREMENT. 8 '5 mn 

 greatest length. (From Keibel and Elze's Normaltafeln. ) Tl 

 fore-limb is distinctly in advance of the hind-limb. Tl 

 second branchial arch has begun $to overlap the third an 

 fourth and to enclose the precervical sinus. The tip of th 

 maxillary process is in contact with the lateral and medij 

 nasal processes at the margins of the olfactory pit. 



EMBRYO, 7*2 mm. (CR), and 8 mm. greatest length. 

 .From Keibel and Elze's Normaltafeln.} The limbs have 

 >egun to fold ventrally. The second arch has completely 

 overlapped the third and fourth which now lie in the 

 trecervical sinus, and the sinus still opens on the surface 

 it the posterior border of the second arch. The lens of 

 he eyeball is very evident, and rudiments of the auricle 

 'f the external ear have appeared on the mandibular or 

 irst, and the hyoid or second arch. 



FIG. 103. EMBRYO, 10'9 mm. (CR) and 11 '5 mm. greates 

 length. (From Keibel and Elze's Normaltafeln). The pre 

 cervical sinus is closed and additional rudiments of th< 

 auricle of the external ear are present on the first am 

 second arches. The anterior nares are no longer visibh 

 from the side. 



