248 
POPULAR SCIENCE REVIEW. 
leaves of very different forms : especially notable in this respect 
is the Euphrates Poplar, Populus euphratica , supposed with 
reason to be the willow mentioned in the Psalms. Occasionally 
the variation is confined to one half of the leaves. A remark- 
able instance of this kind has been noted by A. Braun in a 
species of Irina , where one half of the leaf was undivided, the 
other deeply gashed into narrow segments. 
The history of these variations is pretty much the same in 
all cases. All on a sudden a tree, which heretofore has produced 
shoots and leaves of the usual character, emits shoots with leaves 
of a totally different form. If they be such as the cultivator 
thinks likely to serve his purpose, he takes care to propagate 
them by means of grafts or cuttings. Sometimes variations of 
this character may be reproduced by seed, but there is little 
certainty as to this. The same kind of variation occurs in 
flowers and fruits. In the former it is usually associated 
with distinctly recognisable alterations in the phenomena of 
reproduction, as in what are spoken of as dimorphic or tri- 
morphic flowers, some instances of which have been so carefully 
investigated by Mr. Darwin. To this latter class of bud varia- 
tion we shall do no more than make passing allusion, but there 
are other cases which have apparently no relation to variations 
in the phenomena of fertilisation or reproduction, and which 
are strictly analogous to those already mentioned as occurring 
in the leaves. Every now and then, for instance, two roses of 
different forms and colours will be met with on the same stalk, 
;such as a white moss rose in association with a pink one of a 
-different form and destitute of mossy appendages. We have in 
a former paper in this Journal referred to some of these cases 
and to the famous Cytisus Adami — a laburnum bearing yellow 
.and purple flowers as well as leaves of different character — and 
have also alluded to the alleged causes of these strange pheno- 
mena, on which account it is not necessary now to do more 
than refer to them. What is a rare occurrence in the rose, and 
is only known in one or two species of laburnum, is compa- 
ratively common in the chrysanthemum. There are indeed 
particular varieties of this favourite autumn flower which are 
specially liable to produce flowers of different characters on the 
same branch. Generally speaking, but by no means always, the 
change is confined to the colour of the flower only, and colour, as 
we have seen, is proverbially fickle in flowers. Among com- 
monly cultivated plants azaleas and camellias are peculiarly 
liable to “ sport.” In the former plants indeed one may often 
witness much variation in the shape and colour of individual 
blossoms, and very frequently parti-coloured flowers and others 
intermediate between extreme forms. In the case of the fruit 
similar variations occur — peaches and nectarines on the same 
