370 The Morality of Nature 



known that in some species of animals the germ-cells form 

 certain internal parts of the structure, and so act as somatic 

 cells, but they differ from the somatic cell in the fact that 

 they retain the full endowment of the germ-plasm. In the 

 human body the germ-plasm is probably involved in the sub- 

 stance of several organs of initial vitality, where it continues 

 to develop under the influence of its somatic dependents, 

 receiving through the circulation impressions and records of 

 their experiences, and making new responses; and at last, 

 in the laboratories of the specializing sex organs, resolving 

 itself into the ovum or sperm cells according to its present 

 determinants. Then, in case the normal fertilization occurs, 

 there begins again the construction of a new body in the 

 manner previously studied. The early divisions produce 

 cells of full germ power, and these produce the specialized 

 somatic cells of limited power. 



In due time each and every descendant cell, engaged upon 

 the structure building, must be supposed to come to the 

 end of its energy at about the end of its duties. Those 

 branch germ-plasm cells which emit the formative cells are 

 apparently usually extinct when the human body reaches 

 old age, while evidently the cells of lower order are still 

 active, and some must remain active through old age, for 

 even then the skin and tissues continue growth and renewal. 



It must be especially recalled that in all this development 

 one line at least of cells has continued always fully endowed. 

 When the first germ cell divided into two, at least one of 

 these proceeded in a line unchanged ; destined to maintain the 

 continuous full functional life of all its kind; and this proto- 

 plasm, which must be considered as the human being proper, 



