198 Farmer and Dig by.—On the Cytological Features exhibited by 
When the chromosomes are fully developed it can readily be seen that 
they vary in size (Figs. 8, 10). This difference is obvious both at diakinesis, 
at the equatorial plate stage, and also during the anaphase of the heterotype 
mitosis. Another feature of this division consists in the somewhat irregular 
congregation of the chromosomes at the equatorial plate, and the same 
thing applies to the manner of their separation to their respective poles. It 
thus often happens that several chromosomes lag behind the rest, though 
they ultimately all reach their destination. We call attention to this 
circumstance here because the same irregularities, in an accentuated form, 
occur in both the varietal and in the hybrid plants. 
We have once in this fern met with a simulation of amitosis in the first 
division of the spore mother-cell (Fig. 11). This is of interest, inasmuch as 
it is fairly common in both the sport and the hybrid, where we shall describe 
it at some length. 
The remaining features of this and the homotype division call for 
no special remark here, beyond the mention of the fact that the spores, 
when mature, are commonly fertile. 
Polypodium vulgare, var. elegantissimum. 
This fern produces, as we have already stated, not only the beautifully 
dissected fronds proper to the variety, but also other leaves which lack, 
wholly or in part, the laciniate character. They may be said to have 
‘ reverted ’ more or less completely to the ancestral type. The ‘ reversion * 
may only affect a few pinnae or it may involve the entire frond. 
The sporangia are produced on both the varietal and on the £ reverted ’ 
pinnae, and germination tests revealed the unexpected fact that those borne 
on the ‘ reverted ’ pinnae were more sterile than those obtained from the 
laciniate ones. The fertility in either case is, however, a low one, and 
a large proportion of the spores are seen at a glance to be obviously 
depauperate and valueless. The development of the sporangia usually runs 
through a normal course until the mother-cells of the spores are formed, 
but degeneration commonly sets in during or after synapsis. 
During the early stages of prophase the spindle is developed just as in 
the type form (Figs. 16, 17). The kinoplasmic weft becomes repelled 
at four or more points on the nuclear periphery, and a quadripolar (or 
multipolar) arrangement is the result. The poles subsequently fuse, in the 
manner already described, into a bipolar structure as the nuclear membrane 
disappears. We may remark that we have observed, in another species 
of polypody, P . triparti turn, a case in which the spindle, though often 
bipolar, is sometimes quadripolar. 
When diakinesis passes over, and the chromosomes are moved towards 
the equatorial plane, they present a far greater degree of irregularity 
(Fig. 18) than is the case with the type. By the time that the majority 
