328 
SUMMARY OF CURRENT RESEARCHES RELATING TO 
/3. PhjT’siolog'y. 
Cl) Reproduction and Embryology. 
Sexual Reproduction in Plants.* * * § — Prof. M. Mobius considers that 
there is apparent a general tendency to look upon sexual reproduction 
as the primitive condition, and to regard its absence, at least in multi- 
cellular organisms, as a sign of degeneration. On the other hand he 
instances numerous cases, such as Caulerpa , Laminaria , and most Fungi, 
where the absence of sexual organs coexists with considerable differen- 
tiation. The absence of sexuality in Fungi may be connected with the 
peculiar mode of life, but this cannot apply to Algae ; a detailed account 
is then given of the gradual development of sexuality in Algae as shown 
in living forms. The author regards sexual reproduction as having a 
twofold function, firstly the maintenance of the stability of species by the 
elimination of acquired characters, and secondly the production of new 
varieties or species by the union of different germ-plasms. As regards 
the latter, the author is inclined to lay stress on crossing between 
different species, which he says is more common than is usually supposed. 
He also points out that sexuality, even in plants, is often associated 
with sexual dimorphism, and so with increasing complexity of organi- 
sation. 
Fertilisation and Embryogeny of Ginkgo biloba (Salisbnria).f — 
Mr. Sakugrio Hirase has investigated this subject with a view to filling 
up the gaps in Strasburger’s observations. The chief points of interest 
in his results are that the oosphere does not attain maturity till twenty 
weeks after pollinisation ; that the canal-cell which is formed shortly 
before fertilisation becomes almost at once disorganised ; and that the 
nuclear division which immediately follows fertilisation is not accom- 
panied by the formation of cell-walls until after the eighth bipartition. 
The author notices also the presence of large granules in the cytoplasm 
of the oosphere. According to his observations, these granules arise from 
two sources, from the nucleus of the oosphere, and from the nuclei of the 
cells in the neighbourhood of the archegone, and their function is to 
nourish the oosphere. 
Cross-Fertilisation and Self-Fertilisation. — Herr E. Ule f describes 
a new species of Melastomaceae from Brazil, Purjpurella cleistoflora, in 
which the flowers always remain closed, but in which other points of 
structure appear to point to cross-pollination by means of insects. 
Sig. L. Nicotra § states that in the neighbourhood of Messina the 
open flowers of Oxalis cernua produce no seeds, apparently in conse- 
quence of their occurring only in the short-styled form. The plant does, 
however, also bear fertile cleistogamous flowers. 
Dr. C. A. M. Lindman || finds that honey-bees and Syrphidae are 
abundant visitors of the sweet-chestnut, Gastanea saliva , for the sake of 
the nectar, which is copiously secreted by the disc. 
* Biol. Centralbl., xvi. (1896) pp. 129-53 (10 figs.). 
t Journ. Coll. Sci. Imp. Univ. Japan, viii. part ii. (1895) pp. 307-22 (2 pis.). 
J Ber. Deutsch. Bot. Gesell., xiii. (1895) pp. 415-20 (1 pi.). 
§ Bull. Soc Bot. Ital., 1895, pp. 256-8. 
|| Bot. Centralbl., lxv. (1896) pp. 401-3 (1 fig.). 
