112 COLIST CLOUT'S CALENDAR. 



are perpetually trying to get at the store of sweets 

 which the plant has laid by in the base of its flower to 

 allure the fertilizing bees. But any flower which is thus 

 rifled will never be visited or impregnated by insect visit- 

 ors ; and so those plants whose structure aids them by 

 any chance trick or sport in baffling the ants will be the 

 only ones that can set their seeds and become the parents 

 of future generations. Hence, almost all honey -bearing 

 flowers have inherited some peculiar modification of 

 structure which enables them to set at defiance all such 

 creeping marauders. Many of them have stalks covered 

 with long hairs often star-shaped at the end (as one can 

 see even through a little pocket lens), or tipped on top 

 with small, round, sticky glands. Now, there is nothing 

 that bothers ants so much as hairs : they seem as incapa- 

 ble of getting through them as a cow is incapable of 

 getting through a thickset hedge. Other plants, again, 

 secrete a gummy exudation on the stem, in which the 

 wretched foragers get clogged and slowly killed, like 

 flies on a plate of treacle. But the vetch has few hairs 

 and no sticky glands, so it tries to bribe the ants by 

 throwing them a sop instead. The nectaries on the 

 stipules distract them from the flowers ; and if you 

 watch you will see that the ants never mount the slender 

 flower-stalks at all, but go straight up the main stern 

 from one such extra-floral honey -gland to another. No 

 doubt they never discover the existence of the real flow- 

 ers at all. Thus, by the sacrifice of a little sugar at the 

 base of each flower-stalk, the vetch secures its precious 

 blossoms from robbery and consequent barrenness. 

 Curiously enough, there are two nascent varieties of this 

 common vetch, not yet fully differentiated into species 

 one of them hairy while the other is smooth ; and in 

 almost every case the hairiest specimens, being already 



