1909] SAXTON—WIDDRINGTONIA CUPRESSOIDES 171 
Although in Widdringtonia cupressoides the evidence upon which 
this conclusion rests is perhaps slender, yet the same phenomenon 
has been seen in W. Whytei and in two species of Callitris. In the 
latter abundant evidence of the origin of the binucleate condition 
has been obtained in both C. cupressiforme and C. Muelleri.s Here 
a considerable number of nuclei have been found in every stage of 
karyokinetic division from earliest prophase to fully formed binucleate 
cells. The four-nucleate condition is very much less common in both 
Widdringtonia and Callitris, and it is therefore not surprising that 
a second mitotic division has not been met with, but doubtless it 
_ also occurs. A very limited number of cases is found in which five 
_ huclei are present in a single cell. 
. The number of chromosomes in the division just mentioned is of 
_ course the reduced one. In Callitris both the haploid and diploid 
_ chromosomes have been approximately counted, the latter being 
about 24 and the former almost certainly 12 in both species mentioned. 
In Widdringtonia cupressoides, in one of the two nuclear figures 
_ Mentioned above, the chromosomes were just starting to separate 
a from the equatorial plane, and in the other they had advanced about 
__ half-way to the poles. It was possible to count the group of daughter 
_ chromosomes approximately in three out of the possible four cases, 
_ and the number was about 6 in each case. The sporophytic number 
4 has been found to be about 12 (certainly not more than 14). One 
4 dividing nucleus is figured (fig. 22) in which 12 chromosomes seem 
- clearly indicated; this is from a very young embryo. It is curious 
a in two genera so closely allied as Widdringtonia and Callitris that the 
q number of- chromosomes in the one should be approximately double 
_ that found in the other, but similar differences have been noted 
__ in even more closely related plants (GATES 15, ROSENBERG 32, 33)- 
4 So far as I am aware, no case has previously been recorded in which 
_ 4 multinucleate prothallus persists in a conifer, but this is certainly 
_ the case in Widdringtonia, as fig. 21 (from quite an old prothallus) 
Clearly shows. An entirely binucleate prothallus is present in CryP- 
tomeria at one stage (LAWSON 21), but subsequent cell divisions 
si jap iay metal tl el ARR i Seog oot) )o ap ios i a. 
Peel f ? . sie re seta ene 
both cones 
3 I am not quite certain that the second species is correctly named, but 
MAIDEN 
- foliage seem to agree very closely with description and figures given by 
