MESSMATES, MUTUALISTS, AND PARASITES 97 



Some animals store up seeds and fruit for future use, and as 

 for various reasons many of these escape being eaten, the storing 

 habit undoubtedly promotes dispersal. Squirrels, jays, and many 

 ants may be cited in illustration. The case of ants is peculiarly 

 interesting. According to Kerner's observations the seeds which 

 prove attractive to these little creatures are those which, although 

 smooth, possess a little rough outgrowth technically known as a 

 "caruncle", as in Violet, Greater Celandine, Snowdrop, Peri- 

 winkle, and some Spurges. It is only this caruncle which is 

 eaten, the rest of the seed being left untouched, and capable of 

 germination. 



Besides the seeds and fruits which specially appeal to the 

 appetites of animals, there are many others which become attached 

 to their bodies, and are thus effectively dispersed. This may 

 take place without any special adaptations to clinging, as in the 

 case of the floating seeds of many aquatic plants, which adhere 

 to the plumage of birds, or where moist earth 

 containing seeds sticks to the feet of birds or 

 other animals. 



There are, however, a large number of fruits 

 and seeds which are either sticky or else studded Fi<r Io86 _ Fruitofz ^_ 



with hooks, their chances of transport by animals n*a bonon* (*$} > studded 



L J with glandular hairs 



being thus greatly increased. Stickiness results 

 in many cases from exposure to moisture, as in the seeds of Meadow 

 Saffron (Colchicum) which have often been observed adhering to 

 the feet of sheep, cattle, and horses. A somewhat more special- 

 ized case is afforded by fruits which owe their viscidity to the 

 presence of glandular outgrowths, e.g. Linncza borealis (fig. 1086). 

 A firmer means of attachment is found in seeds and fruits 

 provided with hooks, and its efficiency would seem to be proved 

 by the fact that about ten per cent of Flowering Plants are pro- 

 vided with such arrangements. They have apparently been 

 evolved, at least in many cases, in relation to the hairy coats of 

 Mammals, for they are particularly characteristic of plants of 

 low stature, with which such animals are likely to come into 

 contact. Many examples are found among the members of our 

 native flora, as everyone who knows the country must have 

 observed. The little globular fruits of the Goosegrass or Cleavers 

 (Galium aparine, fig. 1087) are studded with little recurved 

 bristles which prove very effective holdfasts, and the "burrs" 



VOL. IV. 101 



