92 Flowers and their Unbidden Guests. 



about the insects that aKght on the edge of the petals ? 

 If they approach the nectaries from the edge of the 

 out-spread perianth, they find an obstacle in their path 

 in the shape of a trellis, formed by a hair-like fringe 

 given off radially from each nectary (Plate III. fig. 83, 

 longitudinal section of flower ; fig. 84, a single nectary 

 seen from the side turned towards the ovary). This 

 obstacle, however, is not insurmountable ; for the hairs 

 of the fringe neither secrete viscid matter nor end in 

 sharp points, but terminate each in a small globular 

 yellow head. The insects can therefore clamber over 

 the trellis with perfect ease and without any damage 

 whatsoever, and, so reaching the nectary (fig. 84) on 

 the side turned towards the ovary, can get what they 

 sought. But in thus clambering they must also 

 inevitably come so close to the floral centre as to 

 strike either anther or stigma, as the case may be. 

 Whether, therefore, the flying insects alight directly on 

 the centre of the flower, or alight first on the edge of 

 the perianth and then approach the nectar by a round- 

 about way, their ultimate mode of entrance is the same. 

 Very much the same part is played by the long 

 thin twisting trichomes of Campanula barbata. These 

 are given off from the edges and inner surface of the 

 segments of the corolla, and project into the interior of 

 the bell-shaped flower. It is to them that the plant 

 owes its name " barbata." At first sight it might be 

 supposed that these trichomes, which cover in the 



