﻿2 8o BOTANICAL GAZETTE [april 



Fig. io. The granddaughter segments are forming the spirem of the 

 daughter nucleus by uniting end to end; between the daughter spirems 

 extends the system of connecting fibers. X T500. 



Fig. 1 1 . Daughter nucleus seen obliquely from the pole side ; the spirem 

 is arranged chiefly in long and regular turns. X 1750. 



Fig. 12, A multipolar spindle of the second mitosis; the loops and turns 

 of the partly segmented spirem are entangled ; some of the free ends were 

 made by the knife in sectioning; as a rule^ at this stage the spirem is much 

 more entangled and kinked, so that it is impossible to trace the individual 

 pieces; the chromosomes are probably being pushed into the nuclear plate. 



X 1750- 



FiG. 13. The spindle is bipolar, but the chromosomes are not completely 

 oriented into the nuclear plate; it seems also that the spirem is not wholly 

 segmented. 



Figs. 14, 15. The spindle is about mature, and the arrangement of the 

 chromosomes is typical except that they are very often much more irregular, 

 twisted, and kinked ; in these two figures it is clearly seen that some of the 

 segments of the chromosomes are twisted upon each other, while others are 

 separate, lying tangentially {^fig^ 14) upon opposite sides of the equator. 



X 1750- 



Fig. 16, Chromosomes in metakinesis; the separating elements are often 

 variously bent or curved. 



Figs. 17, 18. Two spindles in anaphase; the retreating chromosomes are 

 more or less curved or undulating rods which are almost invariably slightly 

 hooked at the ends to which the fibers are attached. 



Figs. 19-29. Pollen mother-cell of Podophyllu77t peltatiim. Figs. 19-24 

 refer to the first, and 2j-2g to the second division. 



Figs. 19, 20. Mature spindles; \n Jig. ig the chromosomes on the right, 

 and left are ring-shaped; in the central one the segments are in contact at 

 only one end and each is curved ; the picture presented by the nuclear plate 

 oi fig. 20 is perhaps more frequent and typical ; here also the chromosomes 

 adhere at one end only ; the segments are almost invariably curved, and the 

 ends in contact are sometimes fused in such a way as to present a lump or 

 swollen place. X 1500. 



Fig. 21, a and b. Two chromosomes in metakinesis; the second long- 

 tudinal fission is plainly manifested ; the chromosome a was oriented as in 

 fig. 20 : that at b was probably fastened to the spindle by one end, and stood 

 radially to its axis ; the retreating daughter chromosomes of a will be double 

 U's, while those of b will probably give V's, or merely pairs of parallel and 

 contiguous rods, X 1500. 



Figs. 22, 23. Two karyokinetic figures in anaphase; the two grand- 

 daughter segments of each daughter chromosome are clearly seen at this 

 stage; they are either somewhat U-shaped, straight, or slightly curved rods. 

 X 1250. 



