52 
SUMMARY OF CURRENT RESEARCHES RELATING TO 
nucellus giving birtli to it directly. Starch is rapidly formed in the- 
embryo-sac, and plays a very important part in the nutrition Of the- 
embryo ; it is the antipodals that store it up for this purpose. The 
synergids take no part in this process ; the nucleus of one of these goes 
to meet the pollen-tube ; that of the other one drops to the neighbour- 
hood of the oosphere, and remains there until the first bipartition of the 
nucleus of the oosperm. The synergids supply nutriment to the nucleus 
of the pollen-tube, and to the oosperm at the moment of its formation. 
The two polar nuclei, first of all placed at the periphery of the sac, serve 
for its increase ; subsequently they contribute to the nourishment of the 
oosphere. The ovule of the Mesembryanthemaceae is also amphitropous- 
and bitegumented, and displays striking resemblances to that of the 
Cactaceae. The funicle is again strongly developed, and there is a large 
formation of starch in the embryo-sac. The principal differences are — 
the presence of a three-celled cap in the ovary, and the possible fusion of 
the polar nuclei without the pollen-tube reaching the ovule. 
In the Crassulacete the ovule is characterised by the hood of the. 
embryo-sac formed by the epiderm of the nucellus, by the regression of 
the nucellus, and by the presence of an axial conducting system from 
the chalaza to the embryo-sac. The ovule is anatropous and bitegu- 
mented ; the nucellus is greatly reduced ; the embryo-sac is protected* 
but is isolated in the micropylar region ; it receives the nutrient material 
only in its enlarged lower portion. 
The embryo-sac of other succulent plants — Asclepiadese, Euphor- 
biacem, Portulacacese, Liliaceoe, Amaryllideae — likewise contains starch * 
but this is also the case with some plants that are not succulent. 
Significance of Chalazogamy.* — Prof. J. M. Coulter regards ehala- 
zogamy as a purely physiological phenomenon, not involving any such 
change of structure as defines a natural group or indicates a line of 
descent. It ought not, therefore, to be used as an indication of phylo- 
geny, as suggested by Nawaschin. 
Parthenogenesis in Thalictrum.f — Mr. D. F. Day reports the fre- 
quent occurrence of parthenogenesis in the dioecious species Thalictrum 
Fendleri from Colorado. 
(2) Nutrition and Growth (including- Germination, and 
Movements of Fluids). 
Growth of Pines4 — Prof. R. Hartig has investigated the effect on 
the growth of pine-stems of various external influences, such as wounds* 
and the attacks of insects and fungi. Pines attacked by the larva of the 
moth Psilurn monacha show a smaller yearly growth in all parts of 
the stem, especially the lowest. Young trees so attacked may regain their 
strength after a time. A stronger growth on one side of the stem is not. 
the result of a greater development of foliage on that side ; the strongest 
growth is always on the side opposite to the prevalent wind. 
Relation of the Growth of Foliage-Leaves and the Chlorophyll 
Function.! — Prof. D. T. MacDougal gives the results of a series of 
experiments on this subject, made on a variety of plants, especially in 
* Bot. Gazette, xxii. (1896) pp. 227-8. f Tom. cit., p. 241. 
% Forfct. Nat. Zeitschr., 1896, pp. 1-15, 33-45. See Bot. Ztg., liv. (1896) p. 295. 
§ Joum. Linn. Soc. (Bot.), xxxi. (1896) pp. 526-46 (1 pi. and 1 fig.). 
