ANTS AS THE QUESTS OF PLANTS. 827 



a laborer in tlie special field wlio produced results which fell at 

 once into their proper order in his wider synthesis. As sculptors, 

 they carved out shapely stones, from which he, as architect, built 

 his majestic fabric. The total philosophic concept of evolution 

 as a cosmical process one and continuous, from nebula to man, 

 from star to soul, from atom to society we owe to Herbert Spen- 

 cer himself, and to him alone, using as material the final results 

 of innumerable preceding workers and thinkers. Fortnigliily Re- 

 view. 



ANTS AS THE GUESTS OF PLANTS. 



By Prof. M. HEIM. 



THE relations of ants with aphides and other insects have been 

 studied by several authors, and constitute a field of inter- 

 esting observation. The best known are those with the aphides 

 and the cochineals, from which ants derive a food of honeydew. 

 Where these do not abound, certain hemipterous insects take their 

 place. Thus the caterpillar of the Lyccena is said to bear on its 

 latter abdominal segments three or four pairs of projecting pim- 

 ples with a central opening whence little drops of a special liquid 

 exude under the caresses of Formica fusca. It is believed, further, 

 that ants assist these insects in their molting by helping them 

 get rid of their old skin. It seems to be established that ants 

 jjrotect some insects injurious to vegetation against the attacks 

 of their enemies ; in some cases, however, it is probable that they 

 often take juice-sucking insects from young and tender parts to 

 other, older parts of the plant, where they will do less harm, and 

 thus in a measure protect the plant. Ants have been observed 

 thus transporting aphides. 



All insects producing nectar may be regarded, as a whole, as 

 ambulatory nectaries. They are more powerful causes of attrac- 

 tion to ants than the extrafloral nectaries. Scattering themselves 

 nearly all over the surface of the plant, they determine the com- 

 ing and going of the ants, which indirectly protect the whole 

 jjlant. Yet the damage done by the " ambulatory nectaries," 

 which extract the nutritive juices from the plants and cause 

 deformities in their organs, can hardly be said to be compensated 

 by the incidental and uncertain protection which the ants may 

 afford them in other respects. 



The ants which are really protective to plants are not those 

 which obtain their food (indirectly for the most part through the 

 aphides) from the vegetable kingdom, but those which are really 

 carnivorous. These are numerous in temperate climates, and 

 their usefulness to agriculture and sylviculture is incontestable. 



