Origin and Development of the Compositce. 155 
Tablr XV (continued) 
Species 
Numbers 
Gametic Somatic 
References 
S. tcrebintliinaceum 
Ambrosiinae 
8 
16 
Merrell, 77 
Land, 72 
Ishikawa, 66, 67 
Winge, 114 
Xanthium .S truma.fium 
ZlNNMNAE 
18 
Ishikawa, 67 
Zinnia elegans 
Vekbbsininae 
12 
Ishikawa, 67 
Wcdelia prostrata 
15 
Ishikawa, 67 
Helianthus annuus 
Coreopsidinae 
9 
16 ? 
Tahara, 105 
Ishikawa, 67 
Bonicke, 43 
Winge, 114 
Dahlia coronata 
16 
32 
Ishikawa, 66, 67 
Gates, 57 
Winge, 114 
D. variabilis 
32 
64 
ditto 
Dahlia , garden varieties 
such as D.Juarezii and D. 
gracilis believed to be de¬ 
rived from D. variabilis 
and D. coccineum 
32 
64 
Ishikawa, 66, 67 
occurring in Senecio. As Lactuca has been suggested to be the 
primitive genus of the Cichorieae, derived from the Senecioneae, it 
is interesting to note that the most frequently occurring number 
in this genus is 5. In the same genus, Lactuca, both 8 and 9 occur 
also (cp. Erigerou), so it is clear that the number may vary in one 
genus between the various cardinal numbers, 5,8,9. This being so, 
the derivation of the various numbers from the primitive series 
may quite easily follow the derivation already suggested of the 
various tribes from the Senecioneae. 
The various types of hybridisation, especially the forms of 
philozygoty and pathozygoty distinguished by Winge (114, pp. 196- 
201), account for the variation in number within each of the three 
main series. The origin of the 8 and 9 series from the 5 series may 
be accounted for by the passing of n—1 chromosomes to one pole 
and of n + 1 to the other, as observed by Winge ( loc . cit.) in 
Callitriche verna. More unequal division of the chromosomes has 
been observed by Rosenberg (94) in Hieracium ; the variations 
which he describes as semi-heterotypic include the migration of 
3 gemini to one pole and 21 unpaired chromosomes to the other, 
and similar, very unequally balanced numbers. 
C. Latex in the Composite. 
The phyletic value of the facts concerning the distribution of 
latex throughout the family and in the individual plants is consider¬ 
able, but must always be subordinate to that of floral details. Col, 
