and of other related Primula Hybrids . 361 
My thanks are due to the authorities at Kew, through whose courtesy 
it has been possible to obtain buds of the original type form of P. kewensis , 
and of all the crosses made by the foreman, Mr. Coutts, during the year 
1910. 
Messrs. Veitch have kindly supplied material from their stock of seedling 
P. kewensis and of P. kewensis farinosa. 
It is proposed to begin the account of the cytology of this series 
of Primulas with a description of the premeiotic divisions. The seedling 
P. kewensis has been selected for this examination on account of the larger 
size of its nuclei as compared with those of the other forms. This will be 
followed by a review of the meiotic phase of the seed parent, P. floribunda. 
Subsequently that of the pollen parent, P. verticillata ; of the sterile and of 
the fertile P. kewensis ; of P. kewensis farinosa, and of the various crosses 
of 1910 will be dealt with in succession, but only the points of difference in 
the meiotic phase of these as compared with that of the selected type P.flori- 
bunda will be noticed. Then it is proposed to consider briefly the mode of 
union of homologous lengths of spireme in the bivalent combination as 
exhibited in these Primulas, with regard to the 4 parasynaptic ’ and ‘ telo- 
synaptic 5 views. Finally, to survey the cytological work that has been done 
on hybrids, with special reference to the Oenotheras, which have so many 
features in common with the Primulas. 
Premeiotic Divisions. 
It has already been stated that there is a long rest between the pre- 
meiotic and meiotic divisions of these Primulas. Hence, unlike Galtonia (9) 
and other forms, where the one series of divisions passes imperceptibly into 
the other, in Primula there is no possibility of tracing the transition between 
the two. Primula therefore is not illuminating as regards the origin of the 
parallel threads and paired chromatin masses in the heterotype prophases. 
In a telophase of one of the premeiotic or of the somatic divisions, no 
diagrammatic alveolization of the chromosomes is to be found, resulting in 
the formation of two parallel threads (9 and 21), phenomena which are 
so beautifully displayed by the nuclei of some plants. In the Primulas the 
substance of each entire chromosome breaks up, for the most part trans- 
versely, into rounded granular-like portions (PI. XLI, Fig. 1). Thus these 
granules are bits of whole somatic chromosomes, not bits of the longitudinal 
halves of somatic chromosomes. In Primula the granules may fragment 
into smaller and smaller particles, but in this fragmentation it would of 
course be impossible to say whether the division were longitudinal or trans- 
verse. In a late telophase the nucleus is traversed by a very fine arrange- 
ment of threads, and on these threads chromatin granules of various sizes 
are carried (Fig. 2). 
When the nucleus enters upon the prophase, the granules trend 
