316 A CYTOLOGICAL INVESTIGATION OF SOME SPECIES 
1900 the same hybrid was obtained in a larger number of specimens by 
crossing P. floribunda with P. verticillata. All flowers of this hybrid 
were mikrostyle and sterile, so that they could be multiplied asexually 
only. In 1905 a single makrostyle flower was found on such a plant, 
which was subsequently fertilised by pollen of a mikrostyle one. The 
. sowing of the seeds so obtained, gave both mikrostyle and makrostyle 
plants which, after legitimate crossing, gave good seeds. 
The sterile Primula kewensis arisen in 1899 and 1900 proved to be 
diploid and to contain, like its parents, 18 chromosomes in the vegeta- 
tive and 9 in the generative phase. The fertile P. kewensis arisen in 
1905 possesses 18 chromosomes in. the generative and 36 in the vegeta- 
tive phase e. g. is tetraploid. By selection but one other form e. g. 
P. kewensis farinosa has arisen from P. kewensis. By crossing P. ver- 
ticillata with the pale flowered P. floribunda, both of which are diploid, 
subsequently tetraploid plants have been obtained of the habit of P. 
kewensis farinosa. 
By crossing P. verticillata with P. floribunda Miss PELLEW and Miss 
Dicpy 1) have twice still obtained a tetraploid specimen of P. kewen- 
sis. These specimens were fertile and remained constant, but they sup- 
pose that ,parthenogenesis” occurs among P. kewensis. ERNST calls 
this „parthenogenesis’’: ,inducirte Apogamie’’. 
It was shown by an investigation of GREGORY 2) that within Pri- 
mula sinensis a diploid giant-race occurs but that besides, two tetra- 
ploid races exist of this species. One of these races arose in his own cul- 
tures. Of this he says: 
„Iwo non-giant diploid plants were crossed together reciprocally. 
The F, from one of these crosses gave a perfectly normal F,, consisting 
of non-giant plants among which all the expected classes of offspring 
were represented in numbers closely approximating expectation. 
The F, from the reciprocal cross gave no seeds in a cross with one of. 
its parent races and gave only four plants as a result of self-fertiliza- 
tion. These four plants were giants, and from one of them the race has 
been bred.”’ 
1) CAROLINE PELLEW and FLORENCE M. DurHam. The genetic Behaviour of 
the Hybrid Primula Kewensis and its Allies. Journal of Genetics. Vol. V. 1915— 
1916; ps 159.. 
?) R. P. GREGORY. On the Genetics of Tetraploid Plants in Primula sinensis. 
Proceedings of the Royal Society B. Vol. 87. 1914, p. 485. 
