410 
SUMMARY OF CURRENT RESEARCHES RELATING TO 
essential points those of V. H. Blackman on P. sylvestris .* * * § The following- 
is given as a summary of the most important results. While the ventral 
canal-cell usually disappears soon after it is formed, in some cases it 
persists, and its nucleus becomes as large as that of the oosphere, 
passing through a similar developmental history. In the development of 
the oosphere nucleus, the chromatin takes the form of nueleoles, which 
finally collect from all parts of the nucleus to a definite area near the 
centre, and there develop into a typical spirem. The linin often stains 
like chromatin. After the male pronucleus has entered the oosphere 
nucleus, the chromatin of the two pronuclei appears as two distinct 
masses in the spirem stage. Although centrosomes were not positively 
identified, appearances favour the supposition that they may accompany 
the male nuclei. The fate of the spindle indicates that the kinoplasmie 
fibres arise through a transformation of the cytoplasmic reticulum. 
Embryology and Fertilisation of Alnus.f — Prof. S. Nawaschim 
states that, in the mode of formation of the ovule, Alnus viridis resembles 
Gorylus and Carpinus , two or three embryo-sacs being developed. The 
ovules are nearly orthotropous. The pollen-tube descends along almost 
the whole length of the integument in order to reach the chalaza. 
Embryo-sac of Sparganium and Lysichiton.f — In the species of 
Sparganium examined (chiefly S. simplex ), Prof. D. H. Campbell finds a 
remarkable increase in the number of antipodal cells after impregnation.. 
This may reach as high as 150, by far the largest number yet recorded 
in any plant. If impregnation does not take place, they remain small 
in size and few in number. The nearest approach to this phenomenon 
known elsewhere is in Gramineae ; and the author regards these facts as- 
conclusive evidence that the antipodals are something more than rudi- 
mentary survivals of a prothallium. 
In Lysichiton , belonging to the Araccse, the antipodals are of unusual 
size after fertilisation, but the number never exceeds ten. Their nuclei 
reach enormous proportions. The character of the antipodals is quite 
different from that in any other described Angiosperm, most nearly 
approaching that in some Compositae. 
Development of the Pollen-grain and Embryo-sac in Bignonia.§ — 
Mr. B. M. Duggar records the following among other points in the case 
of Bignonia venusta. Before the flower- bud opens, median transverse 
and longitudinal sections of the anther show the pollen-mother-cells 
occupying four boat-shaped layers, each layer a single cell in depth. 
In the microsporanges, both divisions of the pollen-mother-cells are 
complete before there is any differentiation in the megasporange of the 
primitive archespore ; no tapete is cut off. The embryo-sac develops- 
by the immediate growth of the fourth or lowest megaspore in the axial 
row. In the development of the microsporange or pollen-grain, the 
definitive archespore is differentiated at a very early period. No indication 
of a true spirem is seen until after synapsis. In the first division, the 
spindle is truly multipolar. 
* Cf. this Journal, 1898, p. 644. 
f S.B. Bot. Sect. N'aturf.-vers. Kiew, Aug. 26, 1898. See Bot. Centralbl., lxxvii. 
(1899) p. 106. t Cot. Gazette, xxvii (1899) pp. 153-66 (1 pi.). 
§ Bull. Torrey Bot. Club, xxvi. (1899) pp. 89-105 (3 pis.). 
