654 
SUMMARY OF CURRENT RESEARCHES RELATING TO 
into the soil. When the organ attains a certain depth, varying with the 
species, these contractile roots are no longer formed. The observations 
were made on Phsedranassa chlorcicea , Tigridia sp., and Oxcilis elegans. 
Tubers of Helianthus tuberosus.* — Herr G. Meyer asserts that the 
inulin is formed in the older internodes of the aerial stem of the arti- 
choke, and passes from them into the stolons. The thickening of the 
stolons depends on the activity of the original cambium, on the pro- 
duction of parenchymatous tissue from the interfascicular cambium 
inwards and outwards, and on the subsequent elongation of old paren- 
chymatous cells. 
j8. Physiology. 
(1) Reproduction and Embryology. 
Embryology of the Ranunciilacese.j — Prof. D. M. Mottier has 
followed out the development of the embryo-sac and its behaviour 
previous to fertilisation in American species of Eanunculaceae belonging 
to the genera Delphinium, Caltha , Aquilegia, Ranunculus, Anemonella, 
Thalictrum , and Hepatica. 
In Delphinium tricorne the most remarkable phenomenon observed 
was the presence of two and sometimes more initial cells, and their 
development into mature embryo-sacs. The two embryo-sacs were con- 
tinuous for their whole length, separated only by a very thin and 
indistinct membrane. In Caltha palustris there were a large number 
of initial cells forming a massive archespore, and as many as five may 
develope into embryo-sacs. In Aquilegia canadensis, where all the cells 
are very small, the antipodals become enormously enlarged before 
fertilisation ; and this was also the case with the species of Ranunculus 
examined. In Hepatica acutiloba the egg-apparatus and antipodal cells, 
as well as the cavity of the sac itself, become unusually large before 
fertilisation. At the upper ends of the synergids appear a number of 
protoplasmic strands converging to a point, and thus forming a star- 
shaped cap. The cells of the developing embryo and endosperm afford 
favourable objects for the study of karyokinesis. The centrospheres were 
distinctly observed. 
The most important point in these observations is the frequent 
presence of several initial cells, and their development into normal 
embryo-sacs. In Aquilegia a small cell is occasionally cut off from the 
initial cell, and may possibly be regarded as a tapete. 
Embryology of the Hazel.J — According to Herr S. Nawaschin, 
impregnation takes place in the same way in the hazel as in the birch 
and alder, viz. by chalazogamy ; while in other features Corylus presents 
a greater resemblance to Casuarina. The mature ovule contains several 
embryo-sacs, of which only one becomes impregnated. The embryo- 
sacs are developed out of the cells of a tissue which may be compared 
altogether with the “ sporogenous tissue ” of Casuarina. This consists, in 
the hazel, of a number of elliptical or fusiform cells grouped round the 
* Ber. Deutsch. Bot, Gesell., xiii. (1895) pp. 184-5. 
t Bot. Gazette, xx. (1895) pp. 241-8, 296-304 (4 pis.). 
t SB. Naturf. Gesell. St. Petersburg, March 22 (April 3), 1895. See Bot. 
Oentralbl., lxiii. (1895) p. 104. Cf. this Journal, ante, p. 548. 
