11 



The latex tubes may be mentioned as a second example which, 

 after injury, are healed in the-same way by the formation of 

 membrane caps. Tison observed the latter^ in Mortis al ba and 

 others after the dropping of their leaves"*". The latex tubes as 

 well as nettle hairs prove again that even the cells of dicoty- 

 ledons are capable of forming their membranes anew. 



If, by injuring the( cells, we succeed in exposing the proto-" 

 plasts on all sides, as described above for plasmolytio prooesees, 

 we then have a special case, -which, however, does not disclose 

 anything essentially new. Through this injury protoplasffiio 

 masses of various sizes are often extended from th| large cells 

 of the Siphoneae, which given favorable conditions , are capable 

 of enclosing themselves with new cell wallB. 



In this connection it should be noted that many Siphoneae 

 may also heal their wounds in other ways than by reforming the 

 cellt-walls. If a turgid cell of Va lonia utricularis be pricked, 

 a fine stream jets forth. When, howTver^ the j.etting of the 

 liquid is sustained by a gentle finger pressure, it soon ceases 

 and a gall-like protoplasmic plug free from chlorophyll, which 

 closes the wound, is formed at the prick point. Later the for- 

 mation of a new piece of membrane follows this provisional lig- 

 ature. In the case of strong sacs of Bryopsls, after Injury and 

 the resulting ejection of protoplasmic fragments, a plug of a 

 granular substance is formed which I consider disorganized pro- 

 (14) toplasm , The formation of these peculiar stoppage masses in In- 

 jured cells may be followed under the microscope. The production 

 of the granular mass gives an appearance similar to that formed 

 by the hardening of a drop of wax. Sometimes crystals of percep- 

 tible size are formed in this stoppage mass, the growth of which 

 may be followed satisfactorily under the microscope, although 

 all;the processes here described take place in the fraction of 

 a minute. The latex tubes are also closed after injtiry by coag- 

 ulation plugs. 



Among the scar -membranes formed after plasraolysis or after 

 injury, we find some which entirely resemble normal ones in 

 structure and capacity of grov/th, and still others, showing some 

 variations, as, for example, in the above mentioned scar-membrane 

 of Urtica, which remains very delicate and, more noticeably in 

 Algae, in whose cells Klebs found that soft, weakly refractive 

 membranes, ob"fflously very rich in water, were produced after 

 plasmolysis. fSplrogyra, Mesocarpus). Presumably, the action of 

 the foreign medium surrounding the cell (10 to 15 per cent sugar 

 solution) lies at the bottom of this. 



It should be observed still further that all the newly formed 

 membranes are not capable of grov;th. While in many Siphoneae, it 

 may be demonstrated that scar -membranes often make a prolific sur- 

 face growth soon after their formation, still in the case of cell- 

 walls of other plants formed after plasmolysis, this growth is 

 regularly lacking, for example, in the cells of Elodea or Punaria 

 as cited" by Klebs. In the plasmolysed and newly enclosed cells 

 of Oedogonlum., no growth takes place, only division and the forma- 

 tion of Swarm spores. Where growth results, it leads in many 



^ Rech, s, la chute d. feuilles chez les Dlcot. These, 

 Caen 1900. 



^ Compare Klebs and Schmitz in place mentioned. Further 

 Haberlandt, Ueb. die Lage des Kerns in sich entwickelnden Pflanz- 

 enzellen, Ber. d. D» Bot, Ges, 1887, BB. V, p, 211 and others. 



^ Compare Kuster, Ueb, Derbesla and Bryopsls, Ber. d. P, 

 Bot. Ges. 1899, Bd. XVII, p, 77. 



