NOTE. 
NOTE ON A CASE OF DOUBLING OF EMBRYO-SAC, POLLEN-TUBE, 
AND EMBRYO. — While examining material of a Lychnis hybrid with a view 
to discovering the processes which occur in the formation of gametophytes and 
embryo, a curious example of duplicity was observed in an ovule, and is perhaps 
worth recording. The plant examined was a member of the second generation from 
the cross Lychnis alba , Mill, x Lychnis flos-cuculi , Linn., and was a female with white 
flowers, showing a close resemblance to Z. alba . Several flowers were pollinated by 
Z. flos-cuculi and an ovary was fixed forty- two hours later, one of whose ovules 
showed the structure to be described. 
The ovule in question was about the normal size, and in the appearance of the 
nucellus, integuments, and sporophytic tissues generally showed no exceptional 
features when examined in a series of microtome sections. Within the nucellus, 
however, were present two embryo-sacs, roughly equal in size, lying in contact side by 
side in the usual position ; each sac was of about the normal length, but of little more 
than half the normal diameter. 
Into the apex of each embryo-sac had penetrated a pollen-tube whose nuclei had 
been expelled, and whose residual contents had degenerated in the usual fashion. An 
attempt was made to trace these pollen-tubes backwards, but this was found impos- 
sible, owing to crushing, except in the short gap between the micropyle and the apex 
of the nucellus ; here there appeared to be two distinct tubes, but this was very 
difficult to determine and cannot be considered proven. The probability is strongly 
that two separate tubes entered the ovule, and it seems very unlikely that two functional 
apices should have been produced by the branching of a single tube. Moreover, in 
another ovule (with a single embryo-sac) two pollen-tubes were clearly present, 
though only one was functional, the other stopping short half-way through the 
peculiar specialized channel which leads from the apex of the nucellus towards 
the embryo-sac. The occurrence of two pollen-tubes in the ovule with two embryo- 
sacs may therefore be considered as almost certain. 
Within each embryo-sac was found a single synergid, closely pressed against the 
apex of the pollen-tube ; the second synergid had degenerated, as is usual. The 
antipodal cells had also disappeared. 
Each embryo-sac contained a two-celled embryo of the type observed in other 
ovules of the same age. The cell towards the micropyle was already being differentiated 
as the basal cell of the suspensor. The other cell was, as usual, slightly elongated, 
the nucleus surrounded by dense cytoplasm being at its distal end, a large vacuole at 
the proximal. 
Inside one of the embryo-sacs were found four endosperm nuclei — about the 
usual numbei at this stage of embryogeny. The other embryo-sac, however, still 
[Annals of Botany, Vol. XXVI. No. Cl. January, 1912.] 
