cell wall. Representatives of the most varied plant groups, - 

 algae (Vaucherla, Zygnema, Mesocarpus, Spirogyra. Oedogonium, 

 Conferva. Chartophora, Stigeoclonium, Olaaophora) , dosses 

 (Funarifi leaves), ferns, (prothallia of gymnograms) , and iDon- 

 ocotyledonous growths (leaves from Elodea oanadensi s ) . fur- 

 nished results which agreed in all essentiaX point's, To be 

 sure, the formation of the nev? memhrane required a vcrying 

 length of time in different representatives; Vauohoria occasion- 

 ally formed the new Eell covering in 10 per cent glucose within 

 the first hour, Conferva and cells of prothallia aftor 1 to £ 

 days, zygnema needed 3 to 4 days, ceZlS from Funaria and Slodda 

 8 to 10 days and more. On the other hand "it was not possible, 

 by means of plasmolysis in sugar solution, to incite cells of 

 the Desmidiaceae (Desmldium, Euastrum, Gosmarium, Peniun, Pleu- 

 rotaenium, Closterium, fetraemorus) nor of the Diatoms (Melosira) 

 to the formation of nev7 membranes „ Equally without rosult Were 

 the experiments on many prothallia (BleChnum, Ceratopteris) , on 

 Lemna and Vallisneria, as well as on dicotyledons fSymphorxcar- 

 pUs). As far as the latter are concerned, the negative result 

 of the experiments may be due to the manror in which they ;7ere 

 carried on, as chosen hy Klebs, or to the nature of his exper- 

 imental objects. At all events, his supposition that the capa- 

 city for forming new membranes does not extend to dicotyledons 

 generally, is not pertinent in this general conception. The 

 protoplast in root hairs of dicotyledons forms nev/ membranes 

 after the action of plasmolysis. This is true also of the pro- 

 toplast of pollen tubes"*-. Still further, Townsend found the 

 formation of new membranes in plasmolysed sieve tubes in Bryonia 

 and Cucurbita^, Further similar examples will be noted later. 



(12) Plasmolysis is knoT?m to attain varying degrees, depending 



upon the nature and concentration of the solution employed; i.e., 

 the protoplasmic membrane may be loosened from the vmll only in 

 places or it may be drawn together into a ball , which is separ- 

 ated from the cell-wall on all sides. In the first case only a 

 new cap-like layer is produced, at tached on all sides to the 

 old cell-wall which is still in contact with the protoplast; in 

 the second case, a complete sheath is produced around the proto- 

 plasmic mass, 



•'- Compare Palla„ Beob, -lib, Zellhautbildung an des Zellkerns 

 beraubten Protopl. Flora, 1890, Bd, LXXIII, p. 314. Acqua.. Con- 

 trib, alia conosc, d, cellula veget„ Malpighia. 1891, Vol. V p. 

 3, The same process takes place "normally" in the cap-formation 

 of the root hairs of the Java-fern Drymoglossura nixmmularifolium 

 and Db piloselloides (According to Haberlandt. Physiol. Pflanzen- 

 anatomie, 2 Aufl, 1896, p. 192): "By tonger continued drought, 

 the protoplasm; to v/it, of the root hairs which are drying up, 

 together with the cell-nucleus in the basal part of the hair^ is 

 drawn back, above which "becomes noticeable a more or less regu- 

 lar contraction of the body of the hair. At this point a mem- 

 brane cap is then formed, which bounds the capsulated protoplast 

 of the hair from the dried up part. The latter drops off and the 

 resulting root-hair base waits only for the resuscitating drop of 

 water in order tp grow out at once into a new hair." Reinhardic 

 (Plasmolytische Studien z. Kenntnis des Wachstums der Zellmembran, 

 Festschr. f, Schwendener, 1899, p. 425) has already raised the 

 question, whether the cap formations in the bast, (Krabbe, Beitr. 

 z. Kenntnis dor Struktur u. d. Wachstums vegetab, Zellhaute. 

 Pringsheim's Jahrb. f. wiss, Bot., 1887, Bd. XVIII, p, 346) may 

 not also be placed on an equal footing v/ith the above mentioned 

 abnormal formations, 



^ Townsend, Einfl. des Zellkerns auf d, Biic..ung der Zell- 

 haut, Pringsheim's Jahrb. f. wise. Bote. 1897, Bide XXX, p. 484. 



