344 DICOTYLEDONOUS EMBRYO. 
unequal. Again, while the cotyledons usually form the greater 
part of the embryo (jig. 16, c, c) ; in other instances, as in Pekea 
butyrosa (fig. 771, c), they form but a small portion. In Carapa 
(fig. 770), again, the two cotyledons become united more or less 
a Eh cee 
Hies 770; 
Fie. 769. 
Fig. 768. The embryo of the Almond (Prunus Amygdalus), from which 
one of the cotyledons has been removed. c. The cotyledon which has 
been left. 7. Radicle. g. Plumule. f¢. Tigel'um. c’. Scar left by the 
removal of the other cotyledon. Fig. 769. Vertical section of the 
embryo of a species of Hivea. c’. Large cotyledon, ¢. Small cotyledon. 
g. Plumule. 7. Radicle-——Fig. 770, Vertical section of the embryo of 
Carapa guianensis, showing the atmost complete union of the cotyledons, 
the line, ec, only dividing them. 7. Radicle. g. Plumule.— Fig. 771. The 
embryo of Pekea butyrosa. t. Large tigellum. ec. Rudimentary cotyledons. 
completely into one body, so that. the embryo appears to be 
monocotyledonous ; but its nature is readily ascertained by the 
different position of the plumule in the two cases ; thus, in the 
monocotyledonous embryo the 
plumule is situated just below 
the surface (jig. 705, g); but here 
(fig. 770), the plumule, g, is in the 
axis of the cotyledons. 
The cotyledons are sometimes 
altogether absent, as in Cuscuta. 
At other times their number is 
increased, and this may either 
occur aS an irregular character, 
or as a regular condition, as in 
many Coniferze (fig. 772, c), where 
Fic. 772. PIG. Wios 
c 
Fig. 772. The so-called 
polycotyledonousem- 
bryo of a species of 
Pinus beginning to 
germinate. c. Cotyle- 
dons. 7. Radicle. ¢. 
Tigellum.—Fig. 773. 
The embryo of Gera- 
nium molle. c. Coty- 
ledons, each of which 
is somewhat lobed, 
we frequently find six, nine, or 
even fifteen cotyledons ; hence 
such embryos have been termed 
and furnished with a 
Petiola gid Reais polycotyledunous. It seems, how- 
,p. 7. : 
ever, that this appearance of a 
larger number of cotyledons than is usual in Dicotyledonous 
plants, arises from the normal number becoming divided down 
to their base into segments. In all cases where the number 
of cotyledons is thus increased, they are arranged in a whorl 
( fig. 772, c). 
