i86 
NATURE NOTES 
retained in the carpel. In the pea it develops a rather tough 
inner lining to the pod. In the peach this lining becomes the 
“ stone,” the flesh, of course, being the usual central tissue or 
“ mesophyll ” of a leaf. 
In the mulberry, the effect of fertilisation is now seen in the 
calyx, for each flower consists of four sepals and a pistil only ; 
and while the latter ripens into a seed-like achene, the sepals 
become fleshy and deep purple in colour, a dense cluster of them 
constituting the mulberry fruit. 
The pollination may affect the pistil, without any fertilisation 
at all. This is seen in seedless fruits, as in Sultana raisins and 
grocers’ currants, both being grapes ; whilst cucumbers, bananas, 
some oranges, pineapples, &c., often have no seeds at all. A 
similar result often occurs when florists try to hybridise plants, 
by putting the pollen of one species upon the stigmas of another. 
Full-sized fruits may be, and often are formed; but when they 
burst not a trace of a seed may be there. 
Structure of Fruits. — The varieties of fruits are endless. 
They may be dry and bursting, as of a pea, or fleshy and inde- 
hiscent, as are berries. 
Dry Fruits. — Taking a pod to start with, a similar fruit is 
seen in several of the buttercup family, such as the columbine 
which has five carpels in each flower, quite separate : they burst 
down the margins of the carpellary leaf, i.e., inwards. In magno- 
lias similar “ follicles ” occur, but they are so rigid that the seeds 
could not escape, so nature splits them down the back and lets 
them out that way instead. In Nigella, “ love-in-a-mist,” the 
five carpels are united by their edges, and so we get a “ capsule.” 
But there are many sorts of capsules, and various ways of 
bursting ; sometimes by valves, i.e., by splitting off like doors 
from one end to the other, as in wallflowers, willow-herbs, orchis, 
&c. In Cardamine hirsuta and in balsams the valves come off 
elastically, curl up, and so throw the seeds to a great distance. 
A follicle may, however, lead us in another direction, for the 
buttercup family has “achenes” as well as “follicles.” If a 
follicle instead of carrying two rows of seeds, one row on each 
of its two margins, has them reduced to one seed only, then the 
carpel is reduced also and fits this one seed like a tightly fitting 
skin. Thus the achene of the buttercup is formed. 
All sorts of reductions occur. Thus from the Nigella, with 
five coherent carpels forming a capsule, each containing many 
seeds, we may pass to the fruit of the apple, with only two pips 
in each. Again, the five carpels may be and often are reduced to 
two, as in snapdragon, with many seeds in each. Lastly, these 
two coherent carpels may contain only two seeds in each, and 
this is the case with all Labiates, as the deadnettle, and in the 
borage family. One would think that, as no flower of a labiate 
or of this last-named family contains more than four seeds, while 
every flower of the Scrophidarinea; has hundreds, that this family 
would be much more abundant than the former, but it has really 
a less number of species ! 
