326 
SUMMARY OF CURRENT RESEARCHES RELATING TO 
parts of the plant except the stem are modified leaves ” was first made 
by Wolff in 1767. As to the force by which the metamorphoses are 
brought about, the author sums up thus : — “ Whilst we admit that ex- 
ternal conditions and agencies may be the vera causa of any given meta- 
morphosis, we cannot fail to perceive that they constitute but the 
proximate cause, whilst the ultimate cause resides in the organisation of 
the plant itself.” 
Relationship of Phanerogams and Cryptogams.* * * § — Herr W. Belajeff 
gives a careful resume of the development of our knowledge of the mode 
of impregnation in Gymnosperms from the time of Hofmeister to the 
recent discovery of motile antherozoids in the Coniferae and Cycadese, 
which so clearly point to the Gymnosperms forming a connecting link 
between the Pteridophyta and the Angiosperms. 
Evolution of Assimilative Tissue in Sporophytes* — Mr. C. C. 
Curtis discusses the origin of the separation, in the Pteridophyta, of the 
sporogenous tissue into isolated portions (sporanges), and the develop- 
ment of appendages (leaves) from the sporophyte. He regards the 
Filicinm as having but a remote alliance with the Equisetinse and the 
Lycopodinse ; but each of the classes presents features which suggest a 
descent from the Anthocerotete, although the intermediate stages have 
been. hopelessly lost. But among some of the simpler of the eusporan- 
giate Filicinae the relationship appears very manifest, especially in the 
structure of the so-called fertile leaf. The Gymnosperms and Angio- 
sperms only carry out more fully the departure of the Pteridophyta from 
the ancestral anthocerotal type. 
Winter Characters of Sporanges. :}: — Mr. G. Chamberlain has in- 
vestigated the condition in w'hich certain sporanges remain dormant in 
the winter season, both in the higher Cryptogams and in Flowering 
Plants, Gymnosperms, and Angiosperms. He finds that the sporanges 
of different plants pass the winter in very different stages of development, 
though the stage is probably uniform for the same species. A very 
usual halting place in the development of sporanges appears to be the 
spore-mother-cell. 
B. CBYPTOGAMIA. 
Muscineee. 
Bursting of the Antherid in Polytrichum.§— Herr F. Schaar de- 
scribes the mode of escape of the antherozoids in several species of 
Polytrichum, especially P. juniperinum. At the apex of each ripe 
antherid is a cap, formed of cells of the antherid- wall with greatly 
thickened membranes. These cells are entirely devoid of starch, which 
has been used up in the thickening of the walls ; they contain but little 
protoplasm, and no chlorophyll. It is the swelling of these thickened 
walls that plays the greatest part in the bursting of the antherid. Their 
pressure causes a strong tension of the cuticle at the apex of the antherid, 
and this finally bursts. The cell-membranes become gradually converted 
* Biol. Central!)]., xviii. (1898) pp. 209-18. 
t Bull. Torrey Bot. Club, xxv. (1898) pp. 25-9. 
+ Bot. Gazette, xxv. (1898) pp. 124-8 (1 pi.). 
§ Ber. Deutsch. Bot. Gesell., xv. (3897) pp. 479-S2 (1 pi.). 
