Note. 
161 
A PRELIMINARY NOTE ON THE EMBRYO-SAC OF PROTEA LEPI- 
DOCARPON. R.Br. — The Proteaceae form one of the outstanding features of the 
flora of Cape Colony. As very little is known of the structure and development of 
the embryo-sac in the Order, an investigation was commenced on Protea Lepidocarpon , 
one of the commonest and best known of the Cape species. 
It is a xerophytic shrub often attaining a height of eight feet. It usually exhibits 
a subsocial tendency. Each terminal bud gives rise to a capitulum. Several sugar- 
birds and a number of insects visit the flowers in search of the honey which they 
contain. 1 
A preliminary study of Protea grandiflora was made in 1906 by Mr. E. P. 
Phillips, B.A. ; the results agree in the main with those obtained for other species of 
Protea which have been examined. 
The young ovule arises laterally near the top of the ovary, but turns through an 
angle of 90° and soon becomes pendulous. There are two integuments, which arise 
in basipetal succession. While they are making their appearance the sporogenous 
tissue is also becoming differentiated. A small group of large cells situated below the 
hypodermal layer includes one which becomes the megaspore mother-cell. By this 
time a very definite meristematic tissue has arisen at the base of the nucellus. This 
tissue remains active until about the time of fertilization, and owing to its activity the 
ovule becomes about 5 mm. long. The megaspore mother-cell increases in size, and 
divides in the usual manner to a row of four cells. The reduced number of chromo- 
somes is twelve. The four megaspores are readily distinguished from the surrounding 
cells. 
The basal cell of the row rapidly increases in size, while the other three become 
crushed. The single surviving megaspore increases in length very rapidly, and on 
division gives the typical eight-nucleate embryo-sac. The usual polar arrangement 
of the nuclei is very early established. Meanwhile the cells of the nucellus immediately 
surrounding the embryo-sac become densely packed with starch. The growth of the 
sac keeps pace with the elongating nucellus, and at the eight-nucleate stage the former 
is extremely long and narrow, except at the poles, where it is somewhat expanded. 
The inner integument becomes very long and several cells thick, the outer remaining 
only two cells thick. 
The cells of the inner integument surrounding the micropyle are very large and 
glandular, and they dovetail more or less into one another. They are also very 
closely applied to the cells of the tip of the nucellus, which are also somewhat 
glandular in appearance. 
When the embryo-sac has reached its adult form it has forced its way through 
the tip of the nucellus, and its upper end forms a short wide tube projecting into the 
micropylar tube of the sac. The antipodal nuclei disintegrate about the time of 
fertilization. 
Owing to the difficulty of obtaining satisfactory preparations of the very large 
embryo-sac, neither fertilization nor the fusion of the polar nuclei has yet been seen. 
The first recognizable stage of the embryo was a small group of cells, with definite 
1 Scott Elliott, Ornithophilous Flowers in South Africa. Annals of Botany, vol. iv, p. 274. 
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