SPECIES DISTRIBUTION ABOUT PLYMOUTH. 319 
grassy trackways on Dartmoor, with a vegetation considerably 
different from much of the adjacent surface, have been formed by 
sheep and cattle that have frequented these spots, whose repeated 
croppings the heath, ling, and some of the coarser moorland grasses 
have been unable to withstand, so that a way has been opened for 
the appearance of a different set of plants more fitted to bear the 
constant croppings, and constituted to profit by the manure 
deposited by the animals. 
Having very briefly touched on the influence of some animals on 
plant distribution, I will now bring forward a few facts illustrative 
of the work of insects in the same direction. | 
Sir John Lubbock, in his remarkable lecture delivered at Belfast 
during the last meeting of the British Association, observed, 
“Whilst every one knows how important flowers are to insects, but 
comparatively few are aware on the other hand how much flowers 
and went on to speak of the 
”) 
themselves are dependent on insects, 
remarkable ways in which several species are fertilised or crossed 
by bees and other insects. Bearing these remarks in mind, a field 
of red clover (Trifolium pratense), profusely in bloom, with dozens 
of humble bees and a sprinkling of painted lady, or clouded-yellow 
butterflies passing from head to head extracting honey, has a new 
interest both for the botanist and entomologist, since the first feels 
he would like to know something about the insect which fertilises 
the clover, and at the same time the latter becomes desirous to 
learn particulars respecting the plant that supplies these insects 
with their food. The agriculturist, too, should feel interested, 
since in Australia—whither the clover has been brought, but the 
insect that fertilises it exists not—it does not produce any seed ; 
this, therefore, has to be imported for every fresh crop, as is like- 
wise the case with the common scarlet bean. Darwin believes that 
with us the clover is rendered fertile by humble bees, observing 
that the honey bee has too short a proboscis to reach the nectar. 
Remembering this statement, it was with some surprise I noticed 
one day in August last numbers of both honey and humble bees 
gathering from its flowers in a field near Port Wrinkle, in the 
parish of Sheviocke. Careful examination of some heads that 
honey bees had left showed that their flowers had been bitten 
through near the base of the corolla-tube, evidently in order to the 
extraction of the honey through the orifice. Humble bees very 
commonly, though not invariably, obtain honey in this way from 
