TRANSPLANTING NEURAL TUBE OF AMBLYSTOMA 



171 



The sections give an idea of the conditions at various levels 

 as seen in selected sagittal sections. They show all of the im- 

 portant points that have come to light from the complete study 

 of the entire series of sections of this embrj^o and others of the 

 same age. These points may be summarized as follows : 1) Evi- 

 dence of an active growth and differentiation of the original 



Fig. 7 Embryo T.R.3, sagittal sections, t.n., transplanted neural tube? 

 t.s., transplanted somite; p.s., posterior stump. 

 Fig. 8 Embryo T.R.3, sagittal sections. 



anterior end of the transplanted neural tube; 2) the presence 

 of a well-defined connection between the transplant and the 

 anterior stump located to the left of the midhne, that is, toward 

 the original anterior end of the transplant; 3) the absence of any 

 connection between the transplant and the posterior stump; 

 4) evidence of active growth and differentiation in the posterior 

 stump; 5) evidence of progressive atrophy in the transplant to 

 the right of its union with the brain, that is, in the direction of 

 its original posterior end. 



