Chap. VI] 



ANIMALS 



145 



Like the ant-fungi and the acacias referred to, Cecropia affords an 

 exceptional case of the voluntary surrender by the plant of proteid 

 substances even in relatively- 

 large quantity, for Miiller's 

 corpuscles are produced con- 

 tinuously and in profusion. If 

 we cut through the brown 

 velvety coating (Fig. (Si), we 

 see among the hairs numerous 

 densely crowded objects of the 

 kind represented in the various 

 stages of development. Having 

 grown to their full size, these 

 bodies become loose at the base 

 and are pushed to the surface by 

 the pressure of the elastic hairs 

 that are crowded together side 

 by side. Their developmental 

 history, as well as the presence 

 of a stoma at the apex of each, 

 shows that Miiller's corpuscles, 

 like those of Belt, 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 confirmed by the dis- 

 covery in the Corcovado, 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 (Fig. 82). In this case also the young 

 axillary bud presses on the internode and thus 

 causes the formation of an isodiametric de- 

 pression, which subsequently, owing to the 

 longitudinal growth, gives place to a groove. 



SCIIIMPER L 



Fig. 80. Cecropia adenopus. Base of the petiole 

 with pulvinus and Miiller's corpuscles. Natural size. 



Fig. Si. Cecropia adenopus. 

 Transverse section of part of the 

 velvety coating at the base of 

 the petiole, with Miiller's cor- 

 puscles in various stages of de- 

 velopment. Slightly magnified. 



But the original depression 



