.med. 



mmm^ 



Fig. 17. — An organizer graft in the newt (from Diirken, 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 



