

2io BOTANICAL GAZETTE [march 



together through the massing of the linin into a number of lumps cor- 

 responding approximately to the reduced number of chromosomes. 

 These masses probably represent bivalent protochromosomes. 



3. The masses are all united and elongate greatly until a very 

 delicate, continuous spirem is produced, holding a single row of 

 chromatin granules. 



4. After the delicate spirem stage the nuclei in killed material are 

 usually in synizesis. There is no union of two spirems in synizesis. 



5. In living material no synizesis is evident, and the nucleoli are 

 not crowded against the nuclear wall, but usually have a central posi- 

 tion in the nuclear cavity. Synizesis at this as well as at later stagi 

 is an artifact. 



6. The spirem shortens and thickens while the chromatin granules 

 undergo transverse division. It finally orients itself into twelve loops 

 of different shapes and sizes. 



7. The loops are pressed close to the nuclear membrane, forming a 

 rather definite wreathlike circle, and do not radiate from a closely 

 entangled central mass as in Lilium. 



8. The twelve loops break apart, forming the twelve chromosomes 

 four very large, long, twisted chromosomes; three ring-shaped 



chromosomes; and five smaller, irregular, more or less bean-shaped 



chromosomes. 



9. The chromosomes are united by connecting fibers, which appar- 

 ently contract and draw the scattered chromosomes into the equatonal 

 plane while the spindle is elongating. 



10. One or two nucleoli are usually present, which are still norm^ 

 in appearance after the spindle is far advanced in development, 

 nucleoli are sometimes thrown out bodily into the cytoplasm. 



1 1 . The spindle originates as a more or less fibrous layer over 

 surface of the nuclear membrane before that body dissolves, an 

 this stage decided synizesis of the chromatin is often present. 



12. The spindle is bipolar from the first, with no accessor}' sm e 

 poles, the poles appearing at first as two, more or less pointed, dome 

 shaped caps, much the same as in vegetative karyokinesis. . 



13- The spindle fibers are usually most prominent and thic *es 

 the middle, even in the early stages. There are commonly de 

 asters at the poles. 



The 



the 



