RELATIONS BETWEEN THE NUCLEUS AND CYTOPLASMA 53 



portions could form a new cell-wall, and that they did so soon after being 

 plasmolyzed. Palla 1 has, however, observed a formation of a cell-wall around 

 non-nucleated fragments of cytoplasm in hairs, pollen-tubes, leaf-cells, and in a few 

 algae. These results are due, as Townsend 2 has since shown, to the existence of 

 fine, often almost invisible, plasmatic threads, connecting the nucleated and non- 

 nucleated fragments of cytoplasm. No case has as yet been observed in which 

 a non-nucleated mass of cytoplasm has remained capable of secreting a cell-wall 

 around itself, without being in direct connexion with a living nucleus. 



The effect of the injury is, to a certain extent, immediately perceptible. Thus, 

 the two halves of a divided amoeba become at once more or less rounded, but 

 in a minute or two pseudopodia are again formed in both halves (Fig. 2, Hofer, 

 I.e.). The injury may also act as a direct traumatic stimulus, causing instead of 



FlG. a. Amoeba proteus (after Hofer), A immediately, B five minutes after, the separation into two. In A 

 the injury has caused a retraction of the pseudopodia, in B these are formed again in both nucleated and non- 

 nucleated halves. 



a retraction of the pseudopodia an acceleration of the ciliary or streaming 

 movements, when such are present. In all cases the vital activity of the non- 

 nucleated portions gradually decreases, thus causing amongst other things, as 

 Hofer found in the non-nucleated amoebae, a weakening of the digestive power of 

 such fragments. 



A knowledge of the vital actions of which isolated parts are capable 

 is, though useful and interesting, not of paramount importance. The 

 potential powers of the vital mechanism as a whole are exercised and 

 used in a variety of ways, and many forms of vital activity are possible 

 only to the intact protoplast. Thus, it is certainly incorrect to regard the 

 formation of the cell-wall as being a special function of the nucleus simply 

 because in the absence of the latter no cell-wall can be formed. 



Life, growth, and formative changes are possible only when the 



1 Palla, Flora, 1890, p. 314. Similar observations by Acqua, Malphigia, Bd. V. 

 reference by Zimmermann, Beihefte z. Bot. Centralbl., 1894, Bd. iv, p. 85. 



2 Townsend, Jahrb. f. wiss. Bot., 1897, Bd. xxx, p. 484. 



See also the 



