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 to the exact and long-continued researches of Professor Hermann Müller.

1. That the size and colour of a flower are important factors in determining the visits of insects, is shown by the general fact of more insects visiting conspicuous than inconspicuous flowers. As a single instance, the handsome Geranium palustre was observed by Professor Müller to be visited by sixteen different species of insects, the equally showy G. pratense by thirteen species, while the smaller and much less conspicuous G. molle was visited by eight species, and G. pusillum by only one. In many cases, however, a flower may be very attractive to only a few species of insects; and Professor Müller states, as the result of many years' assiduous observation, that "a species of flower is the more visited by insects the more conspicuous it is."

2. Sweet odour is usually supplementary to the attraction of colour. Thus it is rarely present in the largest and most gaudily coloured flowers which inhabit open places, such as poppies, paeonies, sunflowers, and many others; while it is often the accompaniment of inconspicuous flowers, as the mignonette; of such as grow in shady places, as the violet and primrose; and especially of white or yellowish flowers, as the white jasmine, clematis, stephanotis, etc.

3. White flowers are often fertilised by moths, and very frequently give out their scent only by night, as in our butterfly-orchis (Habenaria chlorantha); and they sometimes open only at night, as do many of the evening primroses and other flowers. These flowers are often long tubed in accordance with the length of the moths' probosces, as in the genus Pancratium, our butterfly orchis, white jasmine, and a host of others.

4. Bright red flowers are very attractive to butterflies, and are sometimes specially adapted to be fertilised by them, as in many pinks (Dianthus deltoides, D. superbus, D. atrorubens), the corn-cockle (Lychnis Githago), and many others. Blue flowers are especially attractive to bees and other hymenoptera (though they frequent flowers of all colours), no less than sixty-seven species of this order having been observed to visit the common "sheep's-bit" (Jasione montana). Dull yellow or