TRANSVERSE SECTIONS OF EMBRYO OF 12 MM. 



267 



cells (neuroblasts and spongioblasts) is not very clear. The nuclei are only just 

 beginning to acquire distinct nucleoli, such as would be characteristic of later stages. 

 The nuclei of. the tissues differ markedly from those of the earliest embryonic stages, 

 but can scarcely be said to have assumed in any of the tissues adult characteristics 



N.I i. 





FIG. rqr. Pic tj SERIES 5, SECTION IQS. 



Card', Card", Cardinal vein. EC. Ectoderm, l-'.b. ' te-brain. / /, ; ''undibular gland. A'. 5, Trigeminal gan- 

 glion. iV-7,8, Acustico-fachl ganglim. N.< Ganglion- n of the glosso-pharyngeal nerve. .A T .ic " 

 jug, Jugular ganglion of the vagus i arm. A'.ir, Roo; ><' -ory nerve. Md, MedullaWf 

 gata. Ot, Otocyst. Sir. 'm.iii, . ! vi itriclp. Ven.iv, Fourth ventricle. X - 



Section through 

 section 19 >, and, tii, 

 bring, out 'three >oinis n 



of the Otocyst (Fig. 

 ions belo; 



the 





