392 BOTANY. 



ologists do not agree with Darwin. The latter regards epinasty, hypo- 

 nasty, geotropismus, heliotropismus as modifications of circumnutation, 

 which is caused by an increase of the turgescence of the cells of one 

 side of an organ. In opposition to this view is an important paper by 

 Professor Wiesner, of Vienna, on Das Bewegumjsvermogen der Pflanzen^ 

 who concludes that "circumnutation is not itself the cause, but a deriv- 

 ative; the separate forms of nutation, on the other hand, heliotropis- 

 mus, geotropismus, &c., are the primary piienomena. The single force 

 to which these forms of motion are to be referred is growth itself." 

 Francis Darwin, in a paper in the Botanische Zeitung on Circumnutation 

 in a Unicellular Organ, applies the method adopted in the study of the 

 motions of flowering plants to a fungus, Phycomijces nitens, whose mo- 

 tions he thinks are in all probability to be attributed to circumnutation. 

 The action of gravity on the longitudinal growth of plants has been 

 studied by F. Schwarz, who comes to the conclusion that gravity has 

 no influence on longitudinal growth when it acts in the direction of the 

 longer axis of plant organs. 



The detailed account of Pringsheim's researches on chlorophyl, with 

 regard to which he made several communications to the Berlin Acad- 

 emy in the years 1879-'81, and to which reference has already been made 

 in the Eeport on the Progress of Botany for 1879, was published in full 

 in Pringsheim's Jahrbiicher for the present year, under the title Ueher 

 Lichtwirlmng und GhloropUyllf unction in dcr Pflanzc. It is an elaborate 

 paper, illustrated by IG plates, and gives a full account of the experi- 

 meats made with his special microscopic apparatus. The views of 

 Pringsheim with regard to the chlorophyl grains acting as shields of 

 the protoplasm against too strong light, and his view that hypochlorin 

 is the direct product of the transformation of chlorophyl is not accepted 

 by Pfefler in his Vegetable Physiology, to which reference is made below, 

 nor by Wiesner, who in the main agrees with Pfeffer. In a short but 

 important paper, Dr. K. Brandt states that the chlorophyllaceous bodies 

 found in some animals, as Spongilla and Hydra, are in reality not organs 

 of the animals themselves, but entophytic algse, which evolve oxygen, 

 upon which the animals live. 



In his Physiology, Pfeffer refers to Boehm's view with regard to the 

 movement of water in plants, which he criticises unfavorably, and in 

 reply to this appeared a communication by Boehm in the Botanische 

 Zeitung, in which he supports his original view that the movement is 

 brought about by suction and not by imbibition, as believed by most phy- 

 siologists of the present day, nor, as was formerly supposed, by capillarity. 

 In the Proceedings of the Berlin Academy is a paper by Schwendener 

 on Climhing Plants, in which he treats of the effect of geotroj)ism, the 

 grasping of the support in consequence of the formation of spirals by 

 nutation, &c. The Jenaische Zeitschrift contains an article by Stahl 

 on So-called Compass-plants. In addition to Silphium laciniatnm, the 

 well-known compass-iilant, he found that Lactuca scariola, and to some 



