452 SUMMARY OF CURRENT RESEARCHES RELATING TO 
some other cause ; but the author is unable to confirm the statement of 
Cohn that these organisms are capable of motion only when they are in 
contact with some solid substance. The free-swimming cells never 
maintain a horizontal position for any considerable time, but elevate 
first one end and then the other, and are constantly turning on their 
longer axis. 
Dr. O. Muller, * while confirming Hauptfleisch’s observations on some 
points, differs from him in others. The phenomena are not, he states, 
uniform in all families of diatoms. In the Pinnularieas the motor forces 
are displayed exclusively on the raphe itself, or in close proximity to it. 
In no other region of the cell-wall are motor-phenomena seen. But 
the raphe exhibits different degrees of complexity of structure in dif- 
ferent families. In the raphe of the Ampliiproriese, Khopalodieae, 
Nitzscliieae, Surirelleae, Campylodiscese, and Cymatopleurese, it consists 
of a canal running along the edge and communicating with the interior, 
and may be called a “ canal-raphe.” In this canal (in the Nitzschiem 
and Surirelleae) a longitudinal fissure may be detected, and the structure 
is adapted for the conduction of a current, and for the protrusion through 
the fissure of fine threads of protoplasm. The structure of the raphe of 
the Pinnulariem, on the other hand, with its complicated terminal and 
central nodes, and with the long curved canals passing through them, 
renders the conduction of a current through it and the protrusion of 
protoplasmic filaments extremely improbable. The author rejects the 
theory of Hauptfleisch that the knots observed in these cases are con- 
tracted protoplasmic filaments. No perforations in the cell- wall could 
be detected through which such filaments could protrude ; many of the 
“ knots ” are probably foreign bodies. 
With regard to the gelatinous envelope, Dr. Muller states that it 
frequently entirely disappears under cultivation ; he was unable to 
detect in it any prismatic structure ; it appears to originate in the form 
of drops. The so-called “ protoplasm filaments ” appear not to be fila- 
ments in the true sense of the word, but rather aggregations of granules. 
The author goes into great detail with regard to the mechanics of the 
movement. The raphe of the Naviculeae, especially of the Pinnularieae, 
he describes as a contrivance of the nature of a screw-propeller, which 
forces the current of protoplasm into spiral lines. 
Sporulation of Diatoms.j — L’Abbe Comte F. Castracane claims to 
have observed the mode of propagation by the internal production of 
spores in the following marine species of Diatomacene i—Achnanthes 
brevipes, Biddulpliia Mobilensis , Gocconeis dirupta, Diatoma hyalinum , 
Hemiaulus Hauckii, Licmophora jiabellata , Nitzschia lanceolata, N. maci- 
lenta, Synedra fulgens, Striatella unipunctata. In some of these the 
process of binary division was also seen. 
Rhopalodia, a new Genus of Diatoms. { — On a number of new 
species from East Africa, together with Epitliemia gibba, Dr. 0. Muller 
founds a new genus of Diatomaceae, Bhopalodia , distinguished from 
Epitliemia by the form of the frustule, which, on the valve side is kidney- 
* Ber. Deutscli. Bot. Gesell., xiv. (1896) pp. 54-64, 11 1—28 (2 pis.). Cf. this 
Journal, 1889, p. 793. t La Nuova Notarisia, vii. (1896) pp. 37-41. 
X Engler’s Jalirb., xxii. (1895) p. 54 (2 pis.). 
