THE ENERGY OF THE LIVING PROTOPLASM. 



161 



Plant-cells deprived of their nucleus are incapable of trans- 

 forming starch into cellulose (Klebs). They evidently cannot bring 

 on a sufficient saccharification of the starch granules, to provide 

 the cytoplasm with the necessary amount of sugar. For the 

 lowest animal forms, an analogous case was proved by B. Hofer ; 

 amoebae can no longer digest albuminous particles when deprived 

 of their nucleus. The importance of the nucleus for the secretion 

 processes of animal organisms was also observed by Vcrworn, 

 Balbiani, and Kovschclt. The latter found, for example, consi- 

 derable changes of form of the nuclei in insects during the 

 secretion of chitin. 



The vegetal nucleus seems to be also the manufacturer of 

 the proteids, as first suggested by Strassburger and Schmitz ; 

 at least protein- crystalloids are frequently found in the nuclei 

 of plant-cells, especially in the orders, Oleacece, Scrophularinece, 

 Bignoniacecv , and in the Pteridophytes (Zimmermann) . For, 

 it does not seem probable that this protein has its source in 

 the cytoplasm and is then transported into the nucleus for 

 crystallisation. Again, in germinating seeds, where protein 

 formation from fragments of decomposed reserve-proteids proceeds 

 with considerable readiness, the nuclei (and also the nuc- 

 leoli) increase in size.' 1 ' The most important function of the 

 nucleus, however, is connected with the division and multiplica- 

 tion of cells and with sexual propagation in plants and animals. 



(i) Peters, Botan. Centralbl. 4S, 181. The nuclei are also often relatively large 

 in the epidermis-cells of leaves, which are especially adapted to store up larger 

 quantities of active albumen (Bokorny, Pfl'ug. Arch 53, 142). Also in the cells of 

 glands relatively large nuclei are often present. 



It is also a remarkable observation that plant-cells deprived of their nucleus do 

 not produce any more starch by assimilation. Only certain alga;, containing 

 pyrenoids (Zygnemacea;) have thus far been observed to be exceptions in regard 

 to starch-production under this condition (Klebs). Simpler organisms, like amceb;e 

 and alga?, are especially well suited for experiments with isolated cytoplasm. Klebs 

 has, by plasmolysis, Qeraslmoff by low temperature during the process of karyokinesis, 

 obtained living parts of alga;-cells, or living cells without a nucleus. The life of such 

 cytoplasm, however, did not last longer than about six weeks. On the other hand the 

 nuclei of radiolaria can remain alive, if deprived of the cytoplasm, only 10-15 hours. 

 Nucleus and cytoplasm influence each other by certain of their products (Verwom 

 Pjlug, Arch. 51, 113). 



