Pr. med. 



Sec. med. 



sec. and. 



\l^' ^7-— An organizer graft in the newt (from Durken, after Spemann and 

 Mangold), (a) Shows the neural groove of the host embryo with the induced 

 neural groove on the left, (b) Shows the induced neural groove more clearly. 

 (c) Is a later stage, the host's neural tube is on the right and the induced neural 

 tube runs straight up the middle, (d) Is section with the host's neural tube on 

 the left {pr. med.) and the induced neural tube {sec. med.) on the right, with an 

 induced ear (/. sec. aud.) beside it 



