AVP.J TRANSl^AKENT EMBHYO. 446 



C. Refnoval of the Embryo from the yolk, as in 



II. C. 



D. Surface view of tfie transparent embryo from 



above. 

 Notice : — 



1. General form of the embryo. 



a. Commencing cranial flexure. 



b. The tail and side folds. 



2. Amnion. Notice the inner and outer (false amnion) 

 Kmbs and remove them with a needle. When the 

 amnion has been removed the features of the 

 embryo ■will be much more clearly visible. 



3. The organs of sense. 



a. Eye. Formation of the lens already nearly 



completed. 

 6. Auditory involution, now a deep sac with a 



narrow opening to the exterior. 



4. The brain. 



a. The vesicles of the fore-, mid-, and Idnd-hrain. 

 h. The cerebral vesicle. 



c. The cranial flexure taking place at the mid- 

 brain. 



E. Transparent embryo from below. 

 Manipulation as in II. E. 



Notice ; — 



1. The increase of the head-folds of the somatopleure 

 and splanchnopleure, especially the latter, and the 

 commencement of these folds at the tail. 



