94 ALEXANDER L. BOUNCE 



c. Intranuclear Distribution of Lipid 122 



d. Turnover of Nuclear Lipid 122 



3. Composition of Nuclei with Respect to Nucleic Acid 122 



a. Deoxj'ribonucleic Acid 122 



(1) Percentage of DNA in Cell Nuclei 122 



(2) Amount of DNA per Nucleus 123 



(3) State of DNA in Cell Nuclei 124 



(4) Intracellular Distribution of DNA 124 



b. Ribonucleic Acid (PNA) 125 



(1) Percentage in Cell Nuclei 125 



(2) Intranuclear Distribution of PNA 127 



(3) Turnover Studies as Applied to PNA 127 



4. Composition of the Cell Nucleus with Respect to Proteins 128 



(a) Scheme for Separating Nuclear Protein Fractions 128 



(b) Amount of Total Nuclear Protein 129 



(c) Albumin Content 129 



(d) Globulin Content 129 



(e) Histone Content 129 



(f) Protamine Content of Nuclei of Spermatozoa 130 



(g) Content of Acidic Lipoprotein (Residual Portion) 130 



(h) Turnover Studies 131 



5. Composition with Respect to Enzymes 132 



(a) Oxidative Enzymes 132 



(b) Hydrolases 137 



(c) Enzymes of General Distribution in Tissues Contrasted with En- 

 zymes Peculiar to a Particular Tissue 139 



(d) Enzymes of Nucleic Acid Synthesis 140 



(e) Enzymes of Protein Synthesis 140 



6. ComiDOsition with Respect to Vitamins and Coenzymes 141 



7. Composition with Respect to Minerals 141 



8. Miscellaneous References 142 



III. The Nucleolus and Nucleolar PNA 143 



1. General Remarks 143 



2. Electron Microscopy of Nucleoli 145 



3. Isolation of Nucleoli 145 



4. Chemical Analyses of Isolated Nucleoli 146 



5. Histochemical Studies of Nucleoli 148 



6. Conclusions 149 



IV. Addendum 152 



I. Methods of Isolating Cell Nuclei 



1. Methods Involving the Use of Aqueous Solutions 



a. Limitations of Methods 



The isolation of cell nuclei on a chemical scale can be carried out by 

 methods involving the use of aqueous or nonaqueous media. The use of 

 aqueous media will be considered first, but before the various technical 

 procedures in general use at the present time are discussed, something will 

 be said concerning the limitations imposed by the use of aqueous media. 



