508 
SUMMARY OF CURRENT RESEARCHES RELATING TO 
posed pilei. The following are the characters of the genus : — Stipe 
erect, central, elongate-conical, expanding at the base into an irregular 
disc ; pilei several, imbricated on the stipe, distant, acropetal in develop- 
ment, circular or irregularly reniform, thin, sub-gelatinous ; hymenium 
inferior, tuberculose or with sinuous nodulose ridges, showing a radial 
tendency of arrangement ; basids tetrasporous ; spores continuous, 
brown. 
Protophyta. 
a. Sciiizopliyceae. 
Polycoccus.* — According to M. P. Hariot, this obscure genus of 
Algrn, founded by Kiitzing, which that author regarded as a stage of 
development of higher algae, and which has been described as the algal 
constituent of several lichens, must be abolished. The plant described 
by Kiitzing is nothing but a minute species of Nostoc , indistinguishable 
from N. punctiforme Ktz. ^N. Hederulse B. & F.). 
Movement and Reproduction of Diatoms.t — Sig. L. Macc-hiati gives 
his adhesion to the view that the power of movement of diatoms has its 
source in the contractility of an external “ perifrustular ” layer of proto- 
plasm. This layer he has observed in diatoms belonging to the most 
various families, — Naviculacese, Cymbellace®, Gomphonemacete, Achnan- 
thaceae, Xitzschiaceas, and Surirellaceae. 
Sig. Macchiati thus describes an example of conjugation observed 
in Cymbella Cistula. Two frustules approached and placed themselves 
opposite to one another by the slightly concave parts of the valves. 
They then began to excrete a large quantity of hyaline mucilaginous 
substance, which completely invested them in an ovoid mass. The 
chromatophores of the two frustules then collected in the centre of each, 
in the form of an ellipsoid body, which after a time divided into two 
spherical masses ; these increased considerably in size, and eventually 
escaped from the valves. The four masses then fused together into two, 
and finally into a single globular body. This last inclosed itself in a 
double membrane and became a sporange, within which was developed an 
auxospore. This auxospore, increasing in size, burst the membrane of 
the sporange, and gradually assumed the form of a frustule of Cymbella 
Cistula. 
A different mode of multiplication was observed in a specimen of 
Eantzschia Amphioxys. The protoplasm here divided itself into two 
ellipsoidal masses with numerous oily drops. These masses became 
inclosed with a cellulose wall while within the parent-frustule, afterwards 
escaping from it, after which the membranes became silicified. The 
parent-frustule was not invested with a mucilaginous envelope pre- 
paratory to the division, as in the case of conjugation. 
Schmidt’s Atlas der Diatomaceen-Kunde. — The most recently pub- 
lished part (Hefte 41 and 42) of this magnificent work consists of eight 
plates, containing representations of different views and different forms 
of species of Aulacodiscus , Coscinodiscus , Porodiseus , Anthodiscus, Stephano- 
pyxxs , Craspedoporu8, and Triceratium. 
* Journ. de Bot. (Morot), v. (1891) pp. 29-32. 
+ Nuov. Giorn. Bot. Ital., xxiii. (1891) pp. 175-84. 
