BOTANICAL EVOLUTION. 473 
the work. This is the modified calyx. In all the forms of the order, 
the flowers are crowded together into compact clusters or heads so as 
to become conspicuous, and these heads are encircled by a number of 
special leaves which have thus taken on themselves the function of a 
common calyx. The calyx of each individual flower or floret thus has 
its protective work done for it, and so it either tends to disappear, as 
is the case in the daisy, or it developes into some other organ as in 
the dandelion, where it forms a very beautiful little parachute, 
attached to which the seed is often borne far away from the parent 
plant. The extent to which the thistle has been carried in this and 
the adjacent colonies by this contrivance shows the perfection of the 
arrangement. And the fact that the Composites form the largest and 
most widely dispersed order of flowering-plants is further evidence— 
if more were needed—to the same effect. In Clematis the style 
instead of withering, which is the usual fate of styles, remains 
adherent to the fruit and becomes feathery; in LEpilobium and 
Parsonsia, two very common New Zealand genera, tufts of hair are 
formed on the seeds (not on the fruit), and thus, by different means 
the same result is arrived at. In the Maples or Sycamores the double 
nut-like fruit has its tissue extended out on each side like a wing, and 
when an autumn equinoctial gale sweeps through these trees it 
carries away the whirling fruit far and wide. A similar explanation 
probably serves to explain the thin discs of a familiar garden friend — 
Honesty,—and probably also the flattened-out seeds of New Zealand 
flax and many other common plants. 
Birds are the unconscious agents whereby a large number of 
plants are distributed. We may consider that a very large number of 
succulent fruits are specially developed that they may be attractive to 
birds which eat them, swallowing the stones or seeds, and passing 
them uninjured through the alimentary canal. We have very many 
examples of such fruits in our Flora; in some, the seeds are enclosed 
in a stone as in the cherry or plum, which thus protects them from 
injury, or they are simply imbedded in pulp as in the gooseberry or 
grape. In the latter case it is usually found that the coats of the 
seed are strong enough to be able to withstand any solvent action 
to which they are subjected in the digestive tract of the bird or 
animal which swallows them. For it is clear that many herbivorous 
animals, especially those which do not masticate their food very well, 
do thus act largely as well as birds in spreading seeds abroad. Every 
one is familiar with the number of seeds of weeds which a load of 
stable manure will introduce into a garden; some of these no doubt 
came with the bedding used, but others have undergone digestion in 
the horse’s stomach apparently without suffering in the process. It 
is also usually the case that fruit-eating birds are not provided with 
particularly strong gizzards, and the seeds are not subjected to the 
grinding process which they would undergo in the “mill” of a 
common fowl. In the stone fruits and berries itis the wall of the 
fruit which becomes succulent, but just as often it is some other part. 
Thus in the strawberry the top of the stalk swells up and becomes the 
juicy, edible portion, while the seeds remain enclosed in little hard, 
dry cases on the outside. The rose—a not very distant ally of the 
strawberry—has solved the same problem in a different way. Its 
seeds are also separately enclosed in a dry case, but instead of being 
