SUMMARY AND CONCLUSION 85 



The writer has no doubt that further study of the problem of glacial 

 and postglacial vegetational history, based on additional facts of modern 

 distribution, on better knowledge of plant migration and the ecological 

 requirements of species, and on new evidence from fossils, and carried 

 on by investigators with different viewpoints and different personal 

 experiences, will lead to many important modifications of the outline 

 here presented. The field is large, almost untouched, and of com- 

 pelling interest, and it is hoped that it will attract the attention of 

 students not only in the region here discussed, but elsewhere through 

 the country as well. 



