The Influence of the Nucleus in the Cell 187 



the cells of Spirogyra, the threads which radiate from 

 the nuclear cavity attach themselves especially to the 

 pyrenoids of the chlorophyll bands, and by ramifying, 

 frequently connect several of them directly with the nu- 

 cleus. 36 In cell-formation in those embryo-sacs where 

 the new cells arise in a peripheral layer, after the forma- 

 tion of numerous nuclei, Strasburger has repeatedly de- 

 scribed radiated figures which unite the nuclei, and which 

 are present, not only between the two daughter-cells of 

 a mother-cell, but also are placed between the nuclei that 

 are not so closely related to each other. The repeated 

 studies of this investigator certainly remove all doubt 

 of the fact that along these rays some influence from the 

 nuclei makes itself felt during cell-division. 37 _. 



The multinuclear nature of the coeloblasts, discovered 

 and carefully studied especially by Schmitz, 38 also argues 

 for the great importance of the nucleus. As a rule, here 

 the nuclei do not lie in the moving part of the granular 

 plasm, but in its resting layers. They are arranged 

 evenly at almost equal distances from each other, and 

 are mostly small and so numerous, that every detached 

 piece, if indeed not too small to remain alive, probably 

 always contains one or more nuclei. All parts of the 

 protoplasts can evidently be directly influenced by them. 



Following the observations on uninjured cells, the 

 investigations on injured protoplasts must lastly be dis- 

 cussed. Schmitz has already drawn attention to the fact 

 that the extruded protoplasmic balls of Vaucheria and 

 other Siphonocladiaceae, are enabled to form a new cell- 



86 Pringsheim, N. Ueber Lichtwirkimg und Chlorophyll Function 

 in der Pflanze. Jahrb. Wiss. Bot. 12: 304. 1881. 



37 Cf. e. g. Strasburger, E. Bot. Praktikum, 1 Aufl. p. 610. 



38 Schmitz. Die vielkernigen Zellen der Siphonocladiaceen. Fest- 

 schr. Naturf. Ges. Halle. 1879. 



OF THE 



UNIVERSITY ) 



OF 



.;.^ 



