479 
Anatomy of Teratological Seedlings. IV. 
exarch, are continued downwards without any striking modification, and 
a triarch condition characterizes the remainder of the seedling. The evidence 
provided by the study of a relatively small number of amphisyncotyls 
hardly justifies the putting forward of any decided views as to the effects of 
this type of cotyledonary fusion, but there does seem to be a definite 
tendency towards the modification of the lateral strands, this taking the form 
of relatively early union of these with the midrib instead of their pursuing an 
entirely independent course. 
Two other seedlings remain to be described which show special anato- 
mical peculiarities and which constitute at present more or less isolated 
records. The first of these, ‘ Seedling G ’, is a tricotyl, and exhibits trimerous 
symmetry in the epicotyl (Fig. 84). The general vascular features of each 
cotyledon are apparently quite normal, but the midrib of one retains its 
collateral structure to the base of the petiole when that of the other two is 
distinctly ; double 5 (Fig. 84). As the node is approached the petioles fuse, 
but the adjacent margins of two show delay compared with the remainder 
(Fig. 85). At this level the vascular strands of that cotyledon possessing 
a collateral midrib coalesce to form a tangentially elongated group (Fig. 85), 
which later loses all trace of its triple origin and forms an endarch xylem 
group almost surrounded by phloem (Fig. 86). This type of structure has 
been regarded as an 8 Anemarrhena ’ condition by Lee ( 21 ), Thomas ( 31 ), 
and others, but it is a far cry from a temporary union such as we have here, 
even where it leads to local loss of identity, to the condition recorded by 
Sargant ( 24 ) for Anemarrhena. The subsequent history of the aberrant 
vascular structure is peculiar. It will be perceived that the transition in the 
other two cotyledons is normal, the adjacent laterals of these members 
uniting to form a xylem group in the intercotyledonary plane, and each 
leaving a free lateral on the side adjoining the remaining cotyledon. Near 
the apex of the hypocotyl the bulk of the large strand turns almost hori- 
zontally to unite with one of the free laterals (Fig. 87), whilst at a slightly 
lower level a smaller portion unites with the free lateral of the other 
cotyledon, a small remnant thus being left. A section at this level would 
therefore show the following strands : 
1. A pair of exarch strands derived from the midribs of two of the 
cotyledons (Fig. 88). 
2. A pair of exarch strands derived from the laterals and parts of the 
vascular system of the aberrant cotyledon (Fig. 88). 
3. A strand produced by the union of the adjacent laterals (Fig. 88). 
4. A small strand representing the remnant of the vascular system of 
the aberrant cotyledon. 
Of these, the strand produced by the union of the laterals remains 
endarch and dies out in the upper part of the hypocotyl, the small strand, 
which consists of metaxylem only, sharing the same fate. The four exarch 
I i 2 
