PHYSIOLOGICAL MORPHOLOGY 



with regard to these and other points is only natural, and to be expected. 

 It is, for example, not impossible that the non-nucleated plasma of 

 particular plants may still be able to form a new cell-wall. That a nucleus 

 devoid of cytoplasm soon dies has been determined by Acqua 1 in the case 



of the generative nucleus of the pollen-tube, and by 

 Verworn 2 in that of the nucleus of Protista. Demoor :! 

 has found that the nuclei of the cells of the staminal 

 hairs of Tradescantia may partly, or entirely, complete 

 the process of mitotic division after the cytoplasm has 

 been killed by chloroform or CO 2 . This important 

 result shows that nuclear division is possible without 

 the direct help of the cytoplasm. Moreover, division 

 may take place in an atmosphere of hydrogen, i. e. 

 in the absence of oxygen. Under these conditions, 

 and also when streaming movements are arrested by 

 chloroform, no formation of the cell-plate or cell- 

 wall takes place, these being products of cytoplasmic 

 activity. 



It is clear ; therefore, that metabolic processes 

 may continue for a time in isolated parts, while the 

 fact that any streaming movement which may be 

 shown by isolated cytoplasmic masses ceases in the 

 absence of a supply of oxygen shows that respiration 

 must continue in such parts. There can be no doubt 

 that in the presence of oxygen the isolated nucleus 

 also continues to respire. 



FIG. I. Root hair of Cn- 

 curbita pepo, plasmolyzed by 

 a ten per cent, solution of 

 grape sugar. After three days 

 the nucleated portion (a), as 

 well as the portion (b) in con- 

 nexion with it, have formed 

 a new cell-wall ; no such wall 

 has, however, been formed by 

 the non-nucleated isolated 

 portion (c). 



It is possible, by plasmolyzing a vegetable cell, to 

 separate the protoplasmic contents into nucleated and non- 

 nucleated portions (Fig. i), and by opening such cells these 

 parts may be obtained lying free 4 . Non-nucleated frag- 

 ments may be directly cut from large infusoria, without 

 employing sugar or saline solutions. In all cases, the non- 

 nucleated fragments ultimately die ', but in some of the experiments Klebs per- 

 formed with algae they remained living for as long as six weeks. Klebs (1. c.) 

 found that, in the case of algae and the leaves of mosses, only the nucleated 



1 Acqua, Malpighia, 1^91, Ed. V, p. 21. 



a Verworn, Pfliiger's Archiv f. Physiologic, 1892, Bd. LXI, p. i. 



s Demoor, Sep.-abdr. aus Archives de Biologic, Bd. xin, pp. 72, 75, &c., 1894. From 

 researches carried out in the Bot. Inst., Leipzig. 



4 Klebs, Unters. an d. Bot. Inst. zu Tubingen, iSSS, Bd. II, p. 552 ; Klercker, Eine Methode 

 zur Isolirung lebender Protoplasten, 1892 (Kgl. Vetenskaps-Akad. Forhandlingar, Stockholm). 



1 Schmitz, Festschrift d. Naturforscher-Gesellschaft in Halle, 1879, p. 275; Klebs, I.e.; 

 Haberlandt, Beziehungen zwischen Function und Lage des Zellkernes, 1887, p. 83 u.s. w. 



