DISPERSION OF POLLEN BY ANIMALS. 153 



the flowers, their means of attachment to the blossoms, their fur and bristles for 

 brushing off the pollen, have all their corresponding variations in form and 

 colouring amongst flowers, and consequently there is an equally long and apparently 

 parallel series in the realm of plants. 



Contemporaneously with the opening of the earliest spring flowers occurs the 

 escape of the first pioneer butterflies from their cocoons; the same sunny day 

 which rouses hive-bees and humble-bees from their winter sleep, sees the Willow- 

 catkins protrude from their brown bud-scales and offer their honey and pollen to 

 the world at large. Many flowers which open early in the morning are only visited 

 by particular butterflies which forsake their nocturnal haunts at the same hour; as 

 soon as the flowers close at sunset the insects in question also seek their quarters, 

 fold their wings, and remain the whole night fast asleep. Other flowers do not 

 open till sunset, when day-flying butterflies are already gone to rest, and they are 

 visited by Hawk-moths, Silk-moths, Owlet-moths, and other Noctuse which have 

 remained throughout the day concealed in shady nooks and commence their 

 ramblings when dusk sets in. These instances of the mutual relations existing 

 amongst vital phenomena obtrude themselves annually on the notice of the most 

 superficial observer, and have been described time after time. 



We need not occupy ourselves any longer at the present day with an account of 

 the facts themselves, but rather with the inquiry into the causes both proximate 

 and remote of all phenomena which are presented to our wondering senses. First 

 of all, the question arises: what is it that induces insects and small birds to visit 

 flowers, and what advantage accrues to a plant from the visits with which its 

 flowers are favoured? The answer is, that the inducement is in some cases care 

 of young, in others the desirability of securing themselves against dangers from 

 storms, and, most commonly of all, it is the craving for food. Flowers, however, 

 do not provide animals with breeding-places, with temporary shelter, or suitable 

 nutriment without claiming a reciprocal service, but have their parts so adjusted 

 that their visitors become laden with pollen, which is then transported to other 

 flowers and deposited on their stigmas where it initiates a series of changes result- 

 ing in the setting of the seeds. The next few pages will be devoted to the eluci- 

 dation and proof of this general answer by aid of individual instances. 



As regards the choice of nests for their young it has long been known that the 

 nocturnal Lepidoptera of the genus Dianthoscia, and also some species of the genus 

 Mamestra lay their eggs in the flowers of Caryophyllaceous plants, e.g., in those of 

 the Nottingham Catchfly, the Bladder-campion, Ragged Robin, and Common Soap- 

 wort (Silene nutans, Silene inflata, Lychnis Flos-cuculi, Saponaria officinalis). 

 The eggs, which are brought forth through a comparatively long ovipositor, produce 

 tiny caterpillars which move about freely in the undivided cavity of the ovary, 

 and there enjoy not only complete shelter but suitable nutriment, for they live on 

 the ovules and young seeds which are seated upon the central placenta situated in 

 the middle of the ovary. When they grow up they bite a hole in the side wall of 

 the ovary, creep through it and descend to the ground, where they pass into the 



