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H. L. WIEMAN 



about by the growing brain's extending caudally and denting 

 in the adjacent side of the transplant, without any positive 

 tendency to fusion with the latter. Posteriorly (fig. 3, C), the 

 transplant is entirely free of the neural stump; nor is there any 

 evidence in other sections of the series of any connections what- 

 soever between the posterior stump and the transplant. The 



Fig. 4 A and B, enlargements of transplanted tube of figure 3, A and B, 

 respectively. 



Fig. 5 Embryo T.R.3, operated April 8. A, April 28; B, May 3; C, May 10. 



relation shown in figure 4, B, may represent a first step in the 

 restoration of anatomical continuity between the anterior stump 

 and the transplant, but since it is also true that in other embryos 

 of this series and age the transplant is entirely free of contact 

 with either stump, it would seem that the condition found in 

 T. R. 1 is more or less the result of a chance contact brought 

 about by the rapid growth at this time of the brain stem anterior 



