98 JOUKNAL OF THE ROYAL HORTICULTURAL SOCIETY. 



in triumph to its nest. All the fruit-like bodies do not ripen at once but 

 successively ; so that the ants are kept about the young leaf for some 

 time after it unfolds. They are about one-twelfth of an inch long, and are 

 about one-third of the size of the ants ; so that the ant bearing one away 

 is as heavily laden as a man bearing a large bunch of plantains." * 



As another instance of a domatium, that of the genus Cecrojncijf 

 especially the South Brazilian C. adenopus, may be mentioned. Dr. 

 Schimper thus described it : — t " It carries a slender stem supported 

 on short prop-roots. A few active ants are always running along the 

 branches and petioles. If the tree be somewhat roughly shaken, then 

 from minute holes in the stem and twigs an army of ants rushes out and 

 savagely attacks the disturber. The species is Azteca instahilis, and is 

 one of the most bellicose of ants, its sting being most irritating. The 

 Cecropia provides its guests with a dwelling and food. The centre of the 

 stem is traversed by a transversely divided cavity ; this is not an adapta- 

 tion to the guests. The dwelling existed before the symbiosis. The 

 entrance is at the upper part of the internode. The axillary bud causes a 

 slight indentation, but at the upper end this forms a roundish depression, 

 where the tissues within are less developed, and so afford an easy entrance 

 by boring through it. 



" The ants of the Cecropia devote themselves in their dwellings to the 

 tending of aphidas ; they would seldom leave this work if the fohage did 

 not merit continued attention. The base of the petiole is covered on its 

 dorsal surface with a brown velvety coating upon which, in uninhabited 

 trees, ovoid whitish bodies, 2 mm. (-08 inch) long, lie quite loose. They 

 were called Miiller's corpuscles, after Fritz Miiller, who discovered them. 

 They are absolutely wanting on the surface of the pulvinus of uninhabited 

 trees, because they are continually carried away and eaten by the ants 

 that are always looking for them, just as in Acacia cornigera {sphcero- 

 cephala). They consist, like those of that plant, of delicate parenchyma 

 rich in proteids and oil. Having a stoma at the apex of each, they are to 

 be regarded as metamorphosed glands. They do not, however, fulfil the 

 functions of glands even in their early stages. Whilst normal leaf glands, 

 with this exception, occur only on young leaves and forthwith die, the 

 glands of Cecropia, converted into nutritive bodies for ants, are continually 

 produced during the whole life of the leaf, and are continually shed when 

 they are gorged with albuminoids. 



" The assumption that the entrance-door and Miiller's corpuscles 

 represent adaptations to ants was surprisingly canfirmed by the discovery 

 near Rio de Janeiro of a species of Cecropia devoid, not only of the ants, 

 but also of the entrance-door and of Miiller's corpuscles as well." 



Dr. Schimper describes three other domatia as occurring in the naturally 

 hollow stems of Ficus incequalis (Moracece), Triplaris americana {Poly- 

 gonacece), and Humholdtia laurifolia (Leguminosce), observing that while 

 ants take advantage of the cavity, " the entrance-aperture may safely be 

 described as an adaptation." 



* Fr. Darwin has described the above structures in his paper, " On the Glandular 

 Bodies of Acacia sphcsrocephala and Cecropia peltata serving as Food for Ants etc.," 

 Journ. Linn. Soc. Bot. vol. xv. 1876. 



t Natural order Artocarpacece, or the Breadfruit family. 



I Plant Geography, p. 141. 



