728 Henslow.—The O right of Monocotyledons from Dicotyledons , 
original bicotyledonary structures are to be found in the early history of the 
embryo.’ 1 
Miss Sargant gives a list of Pseudo-monocotyledons, under five orders 
—Fumariaceae, 3; Umbelliferae, 3; Primulaceae, 1; Lentibularineae, 2; 
Nyctagineae, 3—and observes they are ‘also characterized by the early 
formation of tubers [or corms], or at least by the development of a much 
shortened squat axis V 2 
The following is Darwin's observation on Abronia (Nyctagineae) :—‘ In 
A. umbellata and A. arenaria one of the cotyledons is quite rudimentary 
and destitute of a petiole. At first it stood opposite to the larger cotyledon; 
but as the petiole of the latter grew in the same line zvith the hypocotyl [i.e. 
making it to be falsely terminal] the rudiment appeared in older seedlings as 
if seated some way down the hypocotyl. ... In both these species the 
hypocotyl is so much enlarged, especially at a very early age, that it might 
almost be called a corm. ... In Cyclamen persicum, the hypocotyl, even 
while still within the seed, is enlarged into a regular corm. . . . With 
several Cacteae, the hypocotyl is from the first much enlarged, and both 
cotyledons are almost or quite rudimentary, as in Cerens Landbeckei , Rhip - 
satis cassyiha, &c. So, too, is it in Stapelia sarpedon! 3 Darwin reasons as 
to the cause of the enlargement of the hypocotyl, in its being correlated with 
the arrest of one or both the cotyledons, and suggests the necessity of 
storage of food. At the early stage it would seem to be more probably 
water , whether in plants descended from aquatics or habitually living in 
drought. 
The Cyclamen is another genus which has usually only one cotyledon, 
though a second has been seen. From the late Dr. M. T. Masters’ investi¬ 
gations the genus agrees with Monocotyledons in the following details :— 
1. The early disappearance of the primary root. 
2. One cotyledon is normally absent. 
3. The cotyledon acts as an absorbing organ for consuming the endo¬ 
sperm, just as in Trapa and Monocotyledons. 
4. The first leaf is over the site of the missing cotyledon, and the second 
nearly over the existing one. Hence the phyllotaxis begins as J, as in nearly 
all Monocotyledons. 
5. If four leaves occur there is an attempt to return to the §• divergence 
with the persistent quinary arrangement of the flower. 
6. The development of the large corm is analogous to those of 
Iridaceae. 
7. The glabrous, cordate leaf is paralleled by that of Ranunculus Ficaria , 
Nymphaea , Limnanthemum , and Hydrocharis. 
1 Theory of the Origin of Monocotyledons, &c. Ann. of Bot., vol. xvii, p. 69. 
2 Ibid., pp. 76-8. 
3 Movements of Plants, p. 95 ff. (abridged ; my itals.). 
