220 THE BOOK OF NATURE STUDY 



the Dead-nettle. On removing the calyx from around the ovary 

 a yellowish gland will be seen at the base of the latter in front. 

 This is the nectary, and the nectar secreted by it accumulates 

 in the lower portion of the corolla tube. 



If we now look at the flower as a pollination mechanism we 

 shall obtain an explanation of some of the differences between 

 it and the Dead-nettle. The flower of the Bugle is visited by 

 a number of kinds of insects, of which bees are the most im- 

 portant. These come after the nectar stored in the base of the 

 corolla, and, owing to the length of the tube, it is clear that only 

 insects with fairly long tongues can reach the nectar and will 

 visit the flowers. The insect alights on the expanded lower lip, 

 and the back of its head and body will come in contact with the 

 downwardly directed anthers and be dusted with pollen. Since, 

 however, the stigma has its lobes, which are receptive on the 

 inner surface, separated while the pollen is being shed, we might 

 expect that the flower's own pollen would be deposited on the 

 stigma. This may ultimately occur, but cross-pollination is 

 favoured by the position of the stamens. The two shorter 

 stamens, which are at first close together in the middle line, come 

 between the insect and the stigma. In older flowers these 

 stamens diverge somewhat from one another, and the style is no 

 longer supported so that the stigma bends forward. The position 

 that it now occupies is such that it comes in contact with the 

 portion of the insect's back which is dusted with pollen from 

 younger flowers. 



The four lobes of the ovary enlarge after fertilisation, and 

 the ovule within each develops into a seed. The lobes of the 

 fruit do not open to set the seeds free, but the four lobes separate 

 and are shed, each enclosing a single seed. 



While the spread of the Bugle to any distance, and its establish- 

 ment in a new locality, must depend upon the transport of seeds, 

 the local spread of the plant is effected vegetatively. The pros- 

 trate branches, which were seen to be developed at the base of 

 the plant, resemble in general features the erect shoots, but have 

 a thinner stem with long internodes. Their leaves have longer 

 stalks, and twist round so that the blades are exposed to the 

 light. Roots spring from the nodes where they rest on the 



