866 THE DISPERSION OF SPECIES BY MEANS OF FRUITS AND SEEDS. 



the distance of a few leagues at most, in the course of a single year, and that it 

 takes many years to distribute them, step by step, as it were, over large areas. We 

 may reasonably suppose that distribution is effected principally in the direction of 

 those parts of the world towards which thrushes and blackbirds are in the habit of 

 journeying by short daily stages when autumn, the season of the maturity of most 

 fleshy fruits, sets in. 



It is well known that nutcrackers, jays, squirrels, and marmots, keep stores of 

 food in larders, which they fit up in holes in rocks or in the earth or in some other 

 secret hiding-place of the kind, and that such fruits and seeds as they conceal there 

 are liable to be left permanently for one reason or another. The hiding-place 

 may be forgotten, or, as is still more likely, the creature that occupied it may fall 

 a victim to a bird of prey. The fruits and seeds may then germinate in the place 

 of concealment, and, inasmuch as the latter is always more or less distant from 

 the spot whence the fruits were taken, this must also be accounted one of the modes 

 of dispersion of the plants in question. I have myself observed this curious 

 phenomenon also in the case of the dissemination of the Arolla Pine (Piwws Gemhra) 

 by nutcrackers, of Beeches, Oaks, and Hazels by jays, and of Hazels by squirrels. 



The subject of the dispersion of seeds by insects may be most conveniently dealt 

 with in this connection. Otto Kuntze observed how ants fasten on to the pulp 

 which surrounds the seeds of Carica Papaya, and push the seeds before them in 

 conipanies of three, and Lundstrom narrates that the seeds of the Cow-wheat 

 (Melampyrum), after they fall out, are carried off to ant-hills. These statements 

 early directed my attention to the subject of the dispersion of seeds by ants, and I 

 found that the phenomenon occurs on a very large scale. The ant Tetramoriuvi 

 ccespitum, in particular, is indefatigably engaged throughout the summer in 

 dragging seeds to the ant-hill and storing them up there. Other species, which 

 live in holes in the earth, hollow trees, and such places (Lasius niger, Formica 

 rufibarbis, &c.), exhibit this form of activity, but they are much more fastidious 

 than Tetramorium. Many kinds of seed, which are at once pounced upon by the 

 last-named if they are scattered in the path of those insects, are left untouched 

 by other species. So far as my observations go, it is the seeds with smooth external 

 coats, but with large micropylar and hilar caruncles (see p. 425) which are conveyed 

 to the holes, as, for instance, those of Asa/ru7n Europceum and A. Ganadense, Gheli- 

 donium majus, Cyclamen Ev/ropceum, Galanthus nivalis, Mohringia muscosa, 

 Scmguinaria Canadensis, Viola Austriaca and V. odorata, Vinca herbacea and 

 V. minor, and various species of the genus Euphorbia. The Tetramoriv/m showed 

 a preference for the seeds of Sanguinaria Canadensis, which possess a very con- 

 spicuous hilar caruncle. These seeds being comparatively large and heavy, three 

 or four small ants join forces when one is to be transferred to a hole. There can 

 be no doubt that the caruncle, affording as it does an easily accessible supply of 

 food, constitutes the source of attraction to the ants, and induces them to carry off 

 those particular seeds. Neither the smooth coats of the seeds nor their contents 

 are touched by the ants. Only thus can we interpret the fact that the seeds 



