356 The British Association at Birmingham. 
calyx x O. grandiflora two individuals appeared in one family, 
having lata foliage and habit combined with rubricalyx pigmentation. 
This lata rubricalyx type also has 15 chromosomes, showing that in 
addition to the characters inherited from the cross, the lata foliage 
appears whenever the fertilised egg has 15 chromosomes. Such 
cases show definitely that mutation is a process which is indepen¬ 
dent of the combinations of characters such has occur in hybrids. 
The source of the 15 chromosomes was shown earlier to lie in 
occasional irregularities in the distribution of the chromosomes 
during reduction. In such cases two pollen grains of a tetrad 
receive 8 chromosomes and the other two receive 6. When an egg 
having 7 chromosomes is fertilised by a male cell from a pollen 
grain with 8, the resulting individual will have 15 chromosomes and 
the foliage of lata or semilata. The extra chromosome, which is a 
triplicate of a pair already present, is thus associated with the 
development of certain foliage characters in Oenothera in the same 
way that the accessory chromosome when present in duplicate is in 
certain insects associated with the development of female sex 
characters. This is the first case in plants in which a definite 
relation has been shown to exist between a chromosome and 
particular external characters. 
Mr. A. S. Horne contributed some notes on variability in the 
flowers of Stellaria graminea. The diameter of the corolla in 
flowers belonging to individual plants of 5. graminea varies from 4 
to 15 mm., whereas it exceeds 20 mm. in S. palustris. The width 
of the petal segments may reach 0.5 mm., 2 mm., or intermediate 
measurements in 5. graminea, but exceed 2 mm. and may reach 
4 mm. in 5. palustris. The stamens may be all very short (less 
than one-third the length of the sepals) and sterile, or all along 
(exceeding the sepals) and fertile, or of several intermediate types 
in S. graminea. The correlation between these characters was 
explained by means of a table. Plants were treated experimentally 
—transplanted, propagated vegetatively, and seedlings raised. 
In one experiment the flowers of a plant called B, with corolla 
diameter 14.5—15 mm., corolla lobe 1—1.2 mm., and stamens of 
the longest type, changed after 19 days to corolla diameter 6.4 mm., 
corolla lobe 0.7 mm., with stamens correspondingly reduced in size. 
Another form, A, with corolla diameter 9 mm., corolla lobe 1 mm., 
and stamens of intermediate type, remained unchanged. The 
experimentally produced flowers of plant B approximate closely to 
those of very small-flowered plants in nature. 
Prof. F. E. Weiss gave an account of the phenomenon 
of juvenile flowering in Eucalyptus globulus. Some of the most 
striking cases of juvenile flowering were referred to, as for instance 
that of rose seedlings still in possession of their cotyledons and yet 
bearing a terminal flower on a stem only a few centimetres high. 
Several species of Eucalyptus, which show a marked difference 
between the foliage of the immature plant and the mature foliage, 
have been found in nature flowering on small shrub-like plants still 
possessing leaves of the immature type. A plant from Tasmania, 
described by Hooker under the name Eucalyptus Risdoni, was 
regarded by von Muller as only a form of E. amygdalina, differing 
