350 
PLANT STUDIES 
the body of the sporangium (Fig. 311, d), and was at first 
not recognized as being a spore. 
These structures had also received names before they 
were identified with the corresponding structures of the 
lower groups. The megasporophyll was called a carpel, 
the megasporangia ovules, and the megaspore an embryo- 
sac, because the young embryo was observed to develop 
within it (Fig. 310, em}. 
The strobilus of megasporophylls, therefore, may be 
called the carpellate strobilus or carpellate cone. As the 
carpel enters into the organization of a structure known as 
the pistil, to be described later, the cone is often called 
the pistillate cone. As the staminate cone is sometimes 
wrongly called a "male cone," so the carpellate cone is 
wrongly called a " female cone," the 
old idea being that the carpel with 
its ovules represented the female sex 
organ. 
The structure of the megaspo- 
rangium, or ovule, must be known. 
The main body is the nucellus (Figs. 
311, c, 312, nc) ; this sends out from 
near its base an outer membrane 
(integument) which is distinct above 
(Figs. 311, b, 312, i), covering the main 
part of the nucellus and projecting 
beyond its apex as a prominent neck, 
the passage through which to the apex 
of the nucellus is called the micropyle 
("little gate") (Fig. 311, a}. Cen- 
trally placed within the body of the 
nucellus is the conspicuous cavity 
called the embryo-sac (Fig. 311, d), 
in reality the retained megaspore. 
The relations between integument, micropyle, nucellus, 
and embryo-sac should be kept clearly in mind. In the 
PIG. 311. Diagram of the 
carpel structures of pine, 
showing the heavy scale 
(A) which bears the 
ovule (B), in which are 
seen the micropyle (a), 
integument (6), nucellus 
(c), embryo-sac or mega- 
spore (d). MOORE. 
