8i6 
Compton . — An Anatomical Study of 
Carmichaelia australis (Leguminosae). 
A somewhat similar case to that of Lotus. The root of the dicotyl is 
triarch, 1 the xylem being equally shared between the two cotyledons. In 
a single tricotyl the root was also triarch, each cotyledon being supplied by 
one root-pole. 
Helichrysum bracteatum (Compositae). 
It is unfortunate that schizocotyls have not been obtained of species 
with normally a tetrarch symmetry. The nearest approach to this is the 
above plant, the seed of a schizocotylous race being received from Professor 
de Vries. 2 
The root in dicotyls is diarch, but about half-way up the hypocotyl 
two new protoxylem groups appear, one on each side of the xylem-plate, 
these dividing the original two phloems into four, so that what is apparently 
a tetrarch structure results. The original root xylems pass out as the mid- 
ribs of the two cotyledons ; the new xylem groups divide, and half of each 
enters each cotyledon as a lateral nerve, there being no preliminary fusion 
with the midrib (Fig. 40). 
Tricotyls. Material was unfortunately scarce, and only two seedlings 
can be described. These were both complete tricotyls, and their structure 
was on the whole similar. The root was diarch. A third xylem group 
appeared about half-way up the hypocotyl, metaxylem first, protoxylem 
higher up. The lateral cotyledonary traces appeared as usual, these being 
three in number and alternating with the three root-poles. The upper part 
of the hypocotyl was constructed on the triarch plan. In one seedling each 
of the three cotyledons received a whole root-pole and halves of the two 
adjacent lateral cotyledon traces. In the other seedling two of the lateral 
cotyledon traces did not divide, but each passed entire to one of the cotyle- 
dons ; thus two of the cotyledons possessed only a midrib and one lateral 
bundle (Fig. 41 ). 3 
The Literature of Schizocotyly. 
The occurrence of Angiosperm seedlings with an abnormal number of 
cotyledons has attracted the attention of several writers ; and numerous 
notes have been published dealing with the external features of such 
seedlings. Reference may be made to the work of Duchartre (’48), Junger 
(’69-71), Krause (’80), Winkler (’84, ’94), Gain (’00), Thiselton-Dyer (’02), 
Guillaumin (’ll), and Lutz (’ll). From the standpoint of Genetics a systematic 
study of the inheritance of seedling anomalies has been made by de Vries 
1 Compton (’12), p. 43. A rudimentary fourth protoxylem appears at the summit of the 
hypocotyl. 2 de Vries (’ll), p. 430. 
3 A similar variation was noticed in seedlings of Lepidium sativum , where the midrib typically 
gives off a pair of lateral bundles near its base. 
