of the Pollen in certain Sweet-Peas. 157 



Fig. 21. "Emily Henderson." Late anaphase of the heterotype 

 division, showing the V-shaped chromosomes ap- 

 proaching the poles of the spindle, x about 2000. 



,, 22. The same in polar view. 



„ 23. "Emily Henderson." Young nuclei of the pollen grains, 

 showing the formation of a continuous thread through 

 the fusion of the chromosomes. Nucleoli are present. 

 x 1600. 



,, 24. " Emily Henderson." Young pollen grain, showing the 

 nuclear reticulum and a single nucleolus which is con- 

 nected with the network at one point only, x 1600. 



