132 
Reduction in Descent. 
continued comparative work at the structure of angiospermous seedlings is 
likel} 7 to have important results is of even greater interest to the present 
writer, who believes that this hitherto practically untouched field of 
research opens up great possibilities in various directions. 
Before proceeding to criticism of that portion of Miss Sargant’s paper 
to which it is desired to take exception, it may not, perhaps, be considered 
impertinent to express appreciation of the extreme care and thoroughness 
of her work, and of the breadth of view displayed in her treatment of the 
subject, as well as to express the present writer's belief in the important 
nature of the investigation. 
Miss Sargaut has come to the conclusion (a conclusion which the 
present writer has every reason to believe likely to be justified) that the 
symmetry and general construction of the vascular system of the seedling 
in the hiliaceas is a trustworthy phylogenetic character in the evolution of 
that family; she also finds reason to believe, doubtless on very good 
grounds, which will be fully published in a short time, that a certain genus, 
Anemarrhena, shews in the symmetry of its hypocotyledonary vascular 
system a primitive type among the Lihaceae There are two opposed 
collateral bundles in the terminal cotyledon of this plant. These run down 
into the short hypocotyi, where each divides into two, and the four phloems 
so formed are continuous with those of the tetrarch primary root. This 
arrangement suggested to Miss vSargant the possibility that the two 
opposed cot}'ledouary bundles might represent the bundles of two distinct 
cotyledons of a dicotyledonous ancestor. Comparing the arrangement in 
Anemarrhena with that found in Eranthis among the Ranunculaceae (a family 
with several well-known points of resemblance to the Monocotyledons), 
Miss Sargant finds an interesting similarity. 
In Eranthis the petioles of the cotyledons are united throughout their 
length, and the petiolar cylinder so formed contains two opposed bundles 
just like those of the single cotyledon of Anemarrhena. At the base of the 
joined petioles is a minute hypocotyledonary tuber, in which the two 
cotyledon traces split up so as to form four phloems and eight xylems 
“arranged at fairly regular intervals round the periphery of the tuber.” 
Below the tuber is the primary root, which appears to be normally diarch, 1 
a structure, so far as is known, universal in Ranunculaceae, the plane of 
the diarcli xylem plate being coincident with that of the two cotyledonary 
traces. 
Miss vSargant interprets this structure in the light of Anemarrhena as 
being primitively tetrarch, and supposes that the cotyledonary bundles 
are, in fact, double, while the primary root is diarch by reduction. This 
leads to the hypothesis that the Ranunculaceae have been derived from 
a common ancestor with Anemarrhena , an ancestor with typical tetrarch 
symmetiy, the transition from root to shoot taking place, according to 
Van Tieghem’s first type, in which the four phloems run straight up into 
the cotyledons, while the xylems divide and then re-unite in pairs within 
the phloems. 
Now the most striking point about the anatomy of the seedlings of 
the Ranunculaceae is the extreme uniformity of the arrangement of the 
primordial vascular strands. Typical root-structure is maintained by the 
vascular cylinder through the greater portion of the hypocotyi, which 
averages i cm. in length. The two protoxylem strands forming the diarch 
plate pursue a perfectly uniform course into the cotyledons. The two 
phloems each divide into two and the halves pass laterally outwards, 
eventually joining external to the protoxylems to form the two collateral 
bundles of the two cotyledons. Normal stem-structure, so far as the 
primordial cotyledonary traces are concerned, is nowhere found in the 
hypocotyi, but if we consider the bases of the cotyledons it is evident 
that the transition conforms exactly to Van Tieghem’s third type. There 
is absolutely nothing to suggest primitive tetrarchy. 
It is no doubt just possible to interpret the phenomena in the way 
suggested by Miss Sargant. After the structure just described has been 
• There are, however, occasionally indications as of two additional protoxylems in the 
plane at right angles to the plane of the diarcli plate, i.e., immediately internal to 
the phloems. 
