1922] BAILEY—ANT-PLANTS 389 
and feed upon the softer tissues of the Cecropia. Such excavations 
are essential, owing to the fact that the internodal, medullary 
cavity is entirely jacketed by a dense, horny layer of sclerenchyma. 
In the African ant-plants, the ants cut through to the cambium and 
induce the formation of a nutritive callus. In C. angulata the pits 
are not located in the sides of the internodal chamber, but in the 
nodal diaphragms. At the time when the ants begin their excava- 
tions, the nodal partition consists of five distinct layers (figs. 5, 7). 
The soft, internal layer, which is provided with strands of conducting 
tissue and which is fed upon by the coccids, is separated from the 
external layers of porous, medullary tissue by two layers of dense, 
thick walled tissue. The ants remove the two external layers and 
cut circular pits in the underlying sheets of horny sclerenchyma 
(figs. 8,9). The coccids sit in these pits and thrust their setae into 
the succulent tissue which is thus exposed. That the pits are not 
made by the coccids, as suggested by von IHERING, is indicated, 
not only by the fact the delicate sucking mouth parts of these 
insects are not adapted for excavating in dense tissues, but also 
by the fact that I have actually observed the ants in the process 
of excavating them. 
Summary and conclusions 
The theory of myrmecophily, as modified by SCHIMPER, inter- 
prets the structural peculiarities of myrmecophytic species of 
Cecropia as adaptations for enlisting the services of an aggressive 
army of Aztecas which protect their hosts against the attacks of 
the leaf cutting Attine ants. Cleverly conceived and suggestive 
as this Neo-Darwinian hypothesis undoubtedly is, it appears to 
be based upon a series of plausible deductions or teleological infer- 
ences, and is open to serious criticism. The distribution and feed- 
ing habits of the Attine ants in luxuriant, tropical forests are such 
that the ants are not likely to exterminate indigenous species. 
They show no strong preference for the foliage of Cecropia, and 
rarely attack either inhabited or uninhabited trees. Although 
Aztecas tend to prevent other ants from visiting the terminal 
portions of the adult Cecropias, they do not protect the juvenile 
individuals. That the curious prostomata and Miillerian corpuscles 
