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396 396 BIBLIOGRAPHY.

the left or to the right ; that if the direction of the turn of the spiral and of its revolutions on its axis coincide, the plant moves forwards ; if the contrary, backwards : that for each revolution on its axis, the plant progresses or retrogrades to the extent of one turn of the spiral ; that one revolution lasts generally from one to five seconds ; that each plant has a revolving pendulum motion* (Kreispendel-Schwingung), which may take place either at one end or both ; that one such revolution coincides in time with one revolution of the plant on its own axis ; that the revolv- ing pendulum motion may take place either to the left or to the right ; that the direction of the pendulum motion in left-handed spirals is always to the left, in right-handed spirals, sometimes to the left and sometimes to the right.

The second part of the paper is devoted to an inquiry into the probable causes of the motion, the result of which is summed up" as follows, viz. : that special causes of motion, such as cilia, &c. do not exist ; that external influences, such as light, heat, cur- rents of water, &c. are not the cause ; that the origin of the motion must be sought for in the plant itself, and stand in some relation to its vital condition ; that the movements observed in the higher plants (which are also unexplained) cannot be com- pared with those of the OscillarisB ; that endosmose affords no sufficient explanation ; that the resemblance in many respects to animal motion is undeniable, but that there is no sufficient proof to establish the animal nature of the alga or of its movements.

Roper, E. C. 8. — On Triceratimn arcticum. Q. J. M. S. vol. viii. p. 55.

Smith.— -Notes on Diatomacea?, found near Gambia, O. By Professor Hamilton L. Smith, of Kenyon College, Grambia, O. Q. J. M. S. vol. viii. p. 33.

Stizeistberger. — Dr. Ludwig Rabenhorst's Algen Sachsens resp. Mittel-Europa's Decade I — C. Systematisch geordnet (mit Zu- grundelegung eines neuen Systems) von Dr. Ernst Stizenberger. Dresden, 1860. Heinrich.

Venture — Beobachtungen iiber die Fructifications- or gane der Elo- rideen von Dr. Gustav Venturi. Wien. Z. B. Y. Band x. p. 583. This paper relates to the discovery, by the author, of certain organs in Wrangelia penicellata, Polysiphonia elongata, and Calli- thamnion versicolor, which have the appearance of being anthe- riclia. True spermatozoa have not been seen, although in Cal- lithamnion versicolor the upper cells of the antheridia contained minute cellules in which slight movements were observed. Erom the author's account we suspect this motion was only molecular.

in any plane, and is so set in motion as to cause its extremity to describe a circle
 * That is to say, the motion of a pendulum, when the extremity of it can move

or an ellipse.