THE PROTOPLASMIC SYSTEM 



The chemistry of the nucleus is known from studies made 

 especially on blood cells and spermatozoa in which the 

 nuclear material is rich in comparison with the cytoplasmic. 

 Since in the spermatozoa the nuclei (sperm heads) are 

 chromatin in the most condensed state known, their 

 • chemisty is practically the chemistry of chromatin. The 

 following is the chemical constitution of an animal's cell- 

 nucleus (spermhead of the white fish) : 



C96.H,84.N54.O22(C43H57Ni5P4O30)4 " 24H2O 



The nucleus essentially is made up of a protein conjugated 

 with a sugar-containing compound which through the 

 presence of phosphoric acid becomes an acid, nucleic acid. 

 The presence of phosphorus suggests that although lipin 

 may not be present as such in the nucleus, it is necessary for 

 the formation of nucleic acid. Nucleo-protein contains 

 protein and carbohydrates which probably come together 

 through the mediation of phosphorus-containing lipin. 

 In the light of this suggestion the synthesis of nucleo- 

 protein represents the highest chemical activity of the 

 living substance since we see here synthesized the three 

 important substances that distinguish living from non- 

 living matter chemically: protein, carbohydrates and fats. 

 For this reason I consider it an approach to the understand- 

 ing of chemical activities in living matter to study nucleo- 

 protein (and especially nuclein) with respect to its rate and 

 duration of formation and its amount. 



In dividing cells the intact or so-called resting nucleus 

 becomes active and exhibits changes after which it divides. 

 However, the nucleus is not to be thought of as a body 

 implanted in the cytoplasm with no relation to it except 

 during synchronous division. Since in the so-called resting 

 stage the nucleus continually increases in size to the 

 moment in which the activities leading to its division set in 

 we assume that it takes up material from the cytoplasm — • 



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