150 de Fraine .— The Seedling Structure of certain Cadaceae. 
consisted of one or two tracheides only. The formation of these two 
strands from the tubercle and cotyledonary traces has already been 
described in the account of the tubercle, so that no further description is 
necessary, and only the subsequent transition features will be given. 
Echinopsis multiplex , Pfeiff. and Otto. In the upper region of the 
hypocotyl there are present only the two ‘ double ’ bundles (Fig. 13), but 
very soon six epicotylar bundles appear ; they are grouped in threes on 
either side and occupy the intercotyledonary plane. 
Fig. 13. Echinopsis multiplex. Upper part of the hypocotyl. x 109. 
The median bundle of each group of three gradually dies out, the 
remaining two move slowly outwards towards the cotyledonary bundles 
and fuse laterally with them. Towards the base of the hypocotyl £ barrel ’ 
tracheides are developed; at first they bridge the gap which exists between 
the protoxylem and its phloems, but they gradually extend inwards, until 
they occupy most of the central part of the axis. The four phloems do 
not fuse, thus the root shows the arrangement characteristic of the species 
of Cereus. 
Echinopsis Lagermannii. The transition-phenomena in this species 
resemble very closely those just described for E. multiplex , with the excep¬ 
tion that the phloems fuse in pairs, so that the root is diarch. 
Echinopsis tubiflora , Zucc., is similar to E. multiplex . 
Echinocactus. 
The seedling Echinocacti show a close resemblance to those of 
Echinopsis in their external features, but their cotyledons are usually very 
unequal in size ; in E. Ottonis they are reduced to microscopic papillae, 
