THK CANADIAN HORTICULTURIST. 89 



be positively injurious to the flowers themselves, as these would 

 merely rob them of their honey without repaying the debt by caiTying 

 the pollen to others. Flowers therefore have been driven to protect 

 themselves by various devices, such as slippery surface, sticky glands 

 or hedges of hairs, which entirely prevent the ants from obtaining 

 access to the nectary. For the visits of ants to flowers would not 

 only deprive them of their honey, but w^ould prevent the visits of those 

 insects which are so necessary to cross-fertilization. The instance of 

 the mode in which the common Fox-glove excludes the entrance of 

 ants was given; the flower is a close box, which contains the anthers, 

 pistil and honey. It has the specialties of a flower which is adapted 

 for cross-fertilization by insects, color, honey, and the arrangement of 

 stamens and pistils, but it is closed. The flower is adapted to cross- 

 fertilization by humble-ljees, and they alone can force open the box ; 

 to other insects it is closed. Again, the beautiful rosy flowers of the 

 Polygonum A7nphihium are ricli in nectar, and quite unprotected 

 from the visits of creeping insects so long as the plant is gTown in 

 water; the arrangement of the stamens and pistils is such that it cannot 

 fail of cross-fertilization on the visit of any flying insect When, how- 

 ever, this plant is grown on land, and consequently liable to the visits 

 of creeping things, certain hairs terminating in sticky glands are thrown 

 out, effectively barring the entrance of these worse than useless guests. 

 The so called "sleep" of plants is another means of self-defence 

 adopted by those flowers whose fertilization is dependent upon the 

 visits of day insects; while on the other Jiand there are other species 

 of flowers adapted for moths and nocturnal insects, which expand to- 

 wards night, and scent the evening air with delicious perfume. The 

 curious life history of Silene Nutans was then referred to, and the 

 advantages of early rising shown in those flowers which expand early in 

 the morning to receive bees, but close again before the later rising ants 

 are astir. 



Sir John proceeded to discuss the means by which insects provide 

 themselves with means of concealment, by imitating the appearance of 

 plants ; the "walking stick" insect, and many larvae are cases in point 

 Some caterpillars, living on the under side of leaves, not only adapted 

 their color to those leaves, but actually, as their growth increased, 

 altered their markings so as to coincide with the fibres of the leaves. 

 Curiously enough, sometimes bright and striking colors were used as a 



