Allen—Spermatogenesis and Apogamy in Ferns. S3 
nucleus at this stage. This is practically the same number 
which is found throughout the gametophyte and the vegetative 
life of the sporophyte as will be described below. As noted, 
each of these chromosomes is double, as is regularly the case in 
diakinesis. 
At about this stage, kinoplasmic fibres appear in the cyto¬ 
plasm. They are at first few and scattered. Later, they be¬ 
come more numerous and collect into bundles forming a multi¬ 
polar spindle. 
The chromosomes meanwhile have shortened into irregular 
lumps, each composed of two very short, thick rods twisted 
about each other. The appearance of these heterotypic chro¬ 
mosomes is very different from the long slender rods in the 
vegetative mitoses. 
The nuclear membrane now breaks down and the multipolar 
spindle becomes bipolar. It may remain multipolar, but some¬ 
times at least becomes strictly bipolar as in the one drawn 
(figure fifty-seven). During the’formation of the spindle, the 
chromosomes which have hitherto been scattered through the 
large nuclear cavity, come to lie in the equatorial region of the 
spindle. The equatorial plate is frequently irregular in out¬ 
line and forms sometimes a curved surface so that the chromo¬ 
somes do not lie in the same plane. 
As the halves of these double chromosomes are pulled apart, 
the halves themselves become double. In several cases in figure 
fifty-seven the daughter chromosomes are seen to consist of two 
thin parallel rods whose united bulk would about equal one- 
half of the heavy heterotypic chromosome. 
When the chromosomes are drawn back to the poles, the 
daughter nuclei are partially reorganized but no cell division 
takes place. 
In the homoeotypic division which soon follows, the two spin¬ 
dle axes may be placed parallel to each other, or they may lie 
at right angles. In other cases one is oblique to the other. An 
example of the last named case is represented in figure fifty- 
eight. Extending between the two spindles is a thick plate of 
rather dense cytoplasm. The cytoplasm of the remainder of 
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