312 GENERAL PRINCIPLES 



679. Chemical Structure of Protoplasm. — Protoplasm con- 

 tains a very large percentage of water, 70 per cent or more; it 

 is alkaline in reaction in the living condition and contains many 

 mineral salts, which, however, vary greatly with the kind of 

 protoplasm. Among the chemical elements which may be 

 found are phosphorous, manganese, magnesium, calcium, 

 sodium, chlorine, and iron. It does not necessarily follow 

 that these substances form an integral part of the protoplasmic 

 molecule. They may be present as inorganic salt dissolved in 

 the cell sap or even in crystaUine form. Chemically, the living 

 substance is classed with the albumens, but it were perhaps 

 better to say that on analysis it decomposes into a series of albu- 

 minous compounds. These are themselves extremely complex 

 organic bodies, and as yet lie somewhat beyond the range of the 

 chemist's power of analysis. An analysis of egg albumen 

 yielded the result, C72H106N18SO22, though this cannot be re- 

 garded as a correct chemical formula. Nucleoplasm is dis- 

 tinguished from the cytoplasm by the presence of phosphorous. 

 From all that we know regarding protoplasm we are led to re- 

 gard it as an aggregate of many highly complex organic 

 compounds. 



680. Function of Cytoplasm and Nucleus. — Much light has 

 been thrown on the question of the function of cytoplasm and 

 nucleus by a series of simple experiments. If a unicellular 

 organism is cut into two parts, so that the nucleus is also 

 divided, the wound immediately ''heals," and each half 

 regenerates the part cut away so that eventually there are two 

 complete organisms. The operation does not itself greatly 

 injure the cell. If the cell is divided so that all of the nucleus 

 remains in one part, the part without nuclear matter, even 

 though it is the larger part, does not regenerate. It may 

 remain alive for weeks, but ultimately dies. If the nucleus is 

 completely removed from the cytoplasm, both nucleus and 

 cytoplasmic parts die. The death of enucleated portions is 



