ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 
453 
or sickle-shaped, on the pleural side ascus-like, club-shaped, or pear- 
shaped. Most of the species have a somewhat depressed central or two 
terminal nodes, united by a raphe which is not broken by an angle. 
Haviculoid Diatoms.* — In the second and concluding part of this 
most important work, Prof. P. T. Cleve deals with the Naviculm Minus- 
culee, DecussataB, Ileterostichse, Lineolatse (104 species), Punctatae 
(51 species), Lyratae (37 species), and Laevistriatae ; and the genera 
Anomoeoneis ; Pinnularia , divided into the Gracillimae, Capitatae, Diver- 
gentes, Distantes, Tabellarieas, Brevistriatae, Majores, Complexfe, and 
Marinas ; Amphora , divided into Amphora, Diplaniphora (30 species), 
Halamphora (25 species), Oxyamphora, Amblyamphora, Cymbamphora, 
Calamphora, and Archiamphora ; Mastogloia (88 species) ; and the family 
Achnantheae ( Anorthoneis , Bhoicosphenia , Campyloneis , Pleuroneis , Coc- 
coneist , Achnanthes , Heteroneis , Eucocconeis, Microneis, Achnanthidium , 
Disconeis , and Actinoneis. Both recent and fossil species are included ; 
in addition to the diagnosis of each species (in English), an artificial 
key is given for the species of each genus or sub-genus ; some new 
species are described ; and to all the old species the date of first descrip- 
tion is appended. 
0 . Schizomycetes. 
Morphology of Bacteria. f — Prof. M. Lowit has made observations 
on numerous species of bacteria with reference to their structure. By 
treating film preparations with mordants (Loeffler’s and a sulphate of 
copper modification thereof), the bacteria were found to present two 
definite structural areas, a cortical external zone and a central me- 
dullary portion. While the latter stained deeply, the former, though 
distinctly coloured, was relatively much less stained. Apparently this 
cortical layer is the capsule or halo successfully demonstrated. Within 
this cortical area are almost invariably granules. The author regards 
the central body in the light of a nucleus, and the peripheral zone in 
that of the cytoplasm or extra-nuclear plasma of an ordinary cell. 
One feature in the author’s preparations was that flagella were almost 
invariably absent when the outer layer was demonstrable, and vice versa. 
He regards flagella as processes of protoplasm, which become obscured 
under certain circumstances, such as swelling of the cortical layer, or 
damaged by the method of preparation. 
Action of High Pressure on Certain Bacteria4 — According to 
the researches of several investigators, the vitality of bacteria is im- 
paired or extinguished by gases (0 or C0 2 ) at a relatively low pressure. 
M. H. Roger has recently examined into the effect produced on bac- 
teria by compression of the cultivation medium. The bacteria used 
were Staphylococcus aureus , Bacillus coli , Streptococcus erysipelatis, and 
Bacillus anthracis. In bouillon- cultures pressures from 200-250 kg. 
on the square centimetre had no effect whatever. By raising the 
pressure to 3000 kg. to the square centimetre, about one-third of the 
Streptococci were killed and the virulence of the survivors diminished. 
* * Synopsis of the Naviculoid Diatoms,* pt. ii., Stockholm, 1895, 219 pp. 4 pis. 
and numerous figs. 
f Centralbl. f. Bakteriol. u. Parasitenk., l t0 Abt., xix. (1896) pp. 673-86 (1 pi.). 
X Comptes Bendus, cxix. (1894) pp. 963-5. 
1896 2 i 
