PLATE XIII 



Figs, i and 2. — Metaphase and telophase of mitosis of the generative 

 nucleus in the pollen tube [Titlipa, n — 12), showing internal and relic 

 spirals. X 2000. (Upcott, 1936, aceto-carmine.) 



Figs. 3, 4 and 5. — Successive stages in i)rophase uncoiling from 

 Plate II. 



"Fig. 6. — IMajor spirals of Tvadcscantia vivginiana partly uncoiled by 

 "fixing in hot aceto-carmine. (Richardson, unpublished.) x ca. 1500. 



Figs. 7 and 8. — T. virginiana fixed in aceto-carmine. 



Fig. 7. Artificial resting nucleus produced by ammonia pre- 

 treatment of second metaphase chromosomes. Fig. 8. Natural 

 resting nucleus in the pollen grain. (Kuwada and Nakamura, 

 1934 «•) 



