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. 



* That is to say, the motion of a pendulum, when the extremity of it can move 

 in any plane, and is so set in motion as to cause its extremity to describe a circle 



or an ellipse. 



