THE MECHANISM OF LIFE 



521 



in the nucleus any outwardly visible evidences of its metabolism. 

 Nevertheless, it follows clearly from Demoor's experiments that 

 the nucleus also exhibits vital phenomena after the exclusion of 

 the protoplasm. Demoor narcotized cells of Spirogyra with 

 chloroform so that the protoplasm was completely paralysed, and 

 found that, notwithstanding, the nucleus went through all the 

 stages of division undisturbed, and showed the characteristic 

 changes that it exhibits in an uninjured cell in division. In 

 the leucocytes of the frog the nucleus has the power of amoeboid 

 motion, and Demoor was able to paralyse the protoplasm by the 

 use of chloroform without interrupting the movements of the 

 nucleus (Fig. 259). These discoveries show that individual pro- 

 cesses take place in the nucleus in a certain measure independent 

 of the influence of protoplasm. Naturally it cannot be decided 

 at present whether these processes continue only because after the 

 exclusion of the protoplasm there are still contained in the 

 nucleus protoplasmic substances which must be consumed before 

 the processes in question cease, or whether the latter are not 

 directly dependent upon protoplasmic substances. Possibly both 



Fig. 250. — Leucocyte from the frog in a state of chlorof orn. narcosis ; the protoplasm is completely 

 paralysed, while the nucleus still makes amceboid movements. Cf. a, b, c, and d. (After 

 Demoor.) 



cases are here realized ; this appears very probable when it is 

 borne in mind that the nucleus has direct metabolic relations with 

 the external medium, without the mediation of the protoplasm. 

 Without doubt there are substances that pass from the external 

 medium through the protoplasm unchanged into the nucleus, 

 to be employed there for metabolism. This is certainly the 

 case with water in a certain quantity, which is absolutely 

 necessary to every vital process. The water is able to diffuse 

 continually through the cell-membrane into the protoplasm 

 and through the nuclear membrane into the nucleus. It is 

 possible that along with the water many substances which are 

 dissolved in it also come from the outside into the nucleus 

 to engage there in chemical transformation. 



Finally, it may be assumed that all the substances that the 

 nucleus gives off are not employed by the protoplasm for 

 transformations, but that some pass unused through the protoplasm 

 and are transferred to the outside. 



In order to obtain a clear idea of how closely and firmly the 

 nucleus is interwoven into the metabolism of the cell, and what 



