13 



1 



with it one or more nuclei from the mother cell, Klebs has 



treated in detail the significance of the nucleus enucleated 

 cytoplasmic pieces from the ceils of Zygaema, Spirogjnra and 

 Oedogonium, or of Funaria, remained living a long time, to be 

 sure, in cane-sugar solution and, in the case of Spirogyra and 

 Zygnema, formed starch in their chromatophores, but never walls. 

 Haberlandt's experiments^ continue those of Schmitz and Klebs, 

 and give the same results. According to Prpwazek (loc, cit) the 

 greater the number of nuclei contained by the cytoplasmic mass, 

 the more quickly these regenerate^. The theory brought forward 

 by Palla floe, cit.) that cytoplasmic pieces without nuclei are 

 also capable of forming cell-walls has been disproved by the 

 work of Acqua and Townsend (loc. cit.). 



The last named author took an important step forward when he 

 discovered the distant effect of the nucleus. Even pieces of cy- 

 toplasm free from n^tclei ;are capable of forming membranes if the 

 influence of the nucleus can be extended to them by means of con- 

 necting strands from distant portions containing nuclei or from 

 uninjured cells ly:ing at a distance. In this, however, a "living 

 continuity" is necessary,, contact alone heing insufficient for 

 the transference of this Influence, The best data on the influ- 

 ence carried from cell to cell is given by the experiments with 

 sieve tubFS of Cucurbita and Bryonia which lack nuclei, but which 

 may form new walls after plasmolysis. In no case could the for- 

 mation of membranes be observed in the completely isolated, cyto- 

 plasmic masses of the sieve tubes which had passed out of the 

 tubes, Townsend proved the transmission under the influence of 

 neighboring cells containing nuclei, of the wall-forming stimulus 

 to a distance of several millimeters under the influence of 

 neighboring cells containing nuclei., 



Nothing is known as yet of any after effect of the nucleus 



•^ Compare Tagebl. der Berliner Haturf .-Vers. , 1886, p. 194; 

 Ueb. d. Einfluss d. Kernes in der Zelle. Biol, Cbl, 1887, Bd. 

 VII, p. 161; Beitr, z. Phys. d, Pflanzenzelle. Ber. d. B. Bot. 

 Ges., 1887, Bd. V, p. 181; further the detailed publication 

 already quoted. 



2 Besides the above quoted articles compare, Ueb. d. 

 Bezieh. zw. Funktion and lage des Zellke:f;nes b. D„ Pfi. 188''; 

 Ueb, Einkapselung des Protoplasmas mit Rucksicht auf d. Funktion 

 des Zellkernes. Sitz,-Ber, Akad. Wiss, Wien, math.-naturw. Kl,, 

 lfia9, Bd, XCVIII, Abt. 1, p. 190. 



^ Gruber, floe, cit,) states, that pieces of ptotozoa 

 reform complete bodies the more quickly, the larger the nuclear 

 fragment, which they have carried with them. 



By this distant jfeq.ction of the nucleus the above quoted 

 observations of Palla floe, cit.) may well be explained, as well 

 as those of A. Gruttner, Ueb. die Erzeugung von kernlosen 

 Zellen etc., (Diss, Erlangen, 1897). Strumpf tried in another 

 way to harmonize the different results with one another; he ex- 

 presses the ppnjecture that the cytoplasm of young cells, even 

 without nuclei, nay form membranes, but that the old cells need 

 the reaction of the nucleus. (Zur Histologie der Kiefer. Anz. 

 Akad, Wiss. Krakau, 1998, p, 312). 



