in the organisms, make poisons in the very act of living, 

 which make it harder to live. For example, if a number 

 of people are shut up in a room, we know that they give 

 off poisons which check and presently stop life. The same 

 is true of many germs that multiply in our bodies and 

 elsewhere. They quite frequently produce substances that 

 make it harder for themselves to live. If this is true of the 

 cells in our bodies, we can see how by a slow wearing out or 

 a slow poisoning each might do its work less and less well, 

 and thus a decline of the whole organism would follow. 

 Whether this particular explanation is true or not, it is 

 sure that the loss of power, the decline in the work of 

 some of the cells of the body, is responsible for what we 

 call "'old age" in the body as a whole. 



It is not to be imagined that the external conditions 

 are withoiat influence in this. Aging comes faster under 

 some conditions than under others. All the conditions 

 that help to make life possible have some influence on the 

 rate of maturing and the rate of decline. We find, for 

 example, that human beings tend to mature more rapidly 

 in warm countries. You can "force" plants by increasing 

 the heat and moisture. In general, the conditions that 

 hasten maturity also hasten old age. In human beings 

 many internal conditions and habits also hasten these 

 things. Worry, dissipation, overwork, lack of worth-while 

 work, extreme habits of all sorts seem to increase the rate 

 of living and hasten the moment of decline. It is a paying 

 thing to respect these ways of nature. She does not 

 always hurry, but we can never cheat her in the end. 



Death. As the decline passes on, and the income 

 becomes less and less able to meet the outgo, the organism 

 loses more and more its power to adjust itself to the 

 outside conditions and to meet its own needs thereby. 

 Death is merely the entire loss of this power to adapt the 

 internal conditions to the external. Death really begins 

 when the decline begins. It is merely like the final snap 

 of a bar that has been gradually bending toward its 

 breaking point. When the materials, of which the body 

 of a plant or animal is made, lose their power of 

 adjustment the plant or animal is dead. The very 

 conditions that stimulated and supported its life before 

 now cause the decay of the complex materials. 



9. The Cycle. If a body is born, grows into and through 

 youth, matures, grows old and dies, it does not end where 

 it began; except that the matter of which it was made 

 came from the outside world and at death goes back to it. 

 How then can we say we have a cycle? Merely because 

 somewhere along this course, from the early beginnings 

 to death, the individual has the power to produce other 

 young individuals. These are as simple and new as it was 

 at its own beginning. Thus a new start is had, and the 

 cycle is complete. The dying organism does not become 

 young itself; but sometime before death it produces 

 others that are young. This is an interesting thing which 

 we are too much disposed to take for granted; the 

 offspring of parents however old are not of the age of the 

 parents, but are young. Why should the product of a 

 parent forty years old be any less than forty years old? 

 Here is the fountain of perpetual youth. It is the only one 

 we are likely to discover; but it is enough. It makes the 

 eternal circle of new individuals, which supplies the 

 materials by which the evolution of the race goes on. 



CHAPTER TWO. 

 WHAT DO WE MEAN BY REPRODUCTION? 



1. The Individual; Its Upbuilding and Fate. In Chapter 

 One you saw the course of life in the individual. This course 

 includes a small start, an increase, a period of maturity, 

 a decline, and in the end death. This is so universal that 

 we come to take it for granted; and we forget to inquire 

 why it is so. We want now to see a little more closely 

 how the individual behaves in this circle. 



In most cases the start is more modest than was 

 pictured above. Most individuals really start life as a 

 single cell, which is usually scarcely large enough to be 

 seen with the naked eye. This is true even of some of 

 the very largest plants and animals. We think of the oak 

 as starting in an acorn; but really the acorn is not the 

 beginning. The acorn already contains a young oak. 

 The beginning of the new individual was a single cell 

 back in the tissues of the parent tree. From the fate of 

 this cell it is clear that the power of growth and 

 development must be something marvelous. How can a 

 man or a whale or an oak, with billions of cells and 

 weighing many pounds, come from such small beginnings? 



At the bottom of the whole question is this power of 

 the living individual to take up water and other substances, 

 which we call by the general name foods. This power 

 you are quite familiar with, even if we do not understand 

 it. The organism so changes these and combines them as 

 to make new living matter like that of the living object 

 doing it. Jimmie Jones can take beef and pork, potatoes 

 and pop corn, molasses, butter, and milk, and they soon 

 cease to be these particular things, being changed into 

 Jimmie Jones-stuff. Strangely enough beans will become 

 Jimmie just as much as pork will. He puts his stamp on 

 both, and it isn't quite like the stuff in any other living 

 thing. Instead, if we were cannibals, as frogs are, and 

 were to eat the flesh of Jimmie Jones, we would have to 

 change it just as much as he does pork and beans before 

 it would be- like our own bodies. We could do this. All 

 living things have this power. We call it assimilation. 



2. The Selfishness of This Process. It is quite clear 

 that this ability to get and use and change other things 

 into one's own substance is a very selfish power. It looks 

 purely to upbuilding the individual. This seeks income 

 rather than outgo. The appetites and longings, which 

 we know as hunger and thirst, exist in order that the 

 individual may be driven to do the work necessary to 

 grow and build up the self. This is the reason that a boy 

 is always hungry. The instincts for taking food are the 

 first and most basal that animals have, because the 

 building up of the self is the very first work they must do. 

 If they do not do this they will never be able to do 

 anything else. We may say that individual selfishness 

 then is the first step in life. While this is true, we have 

 seen that the individual, in spite of this self-care, finally 

 declines and dies. 



3. The Outcome of Income. The natural result of 

 assimilation therefore is growth, and then more growth. 

 But naturally organisms cannot very well go on forever 

 growing. There must be some sort of an outgo if any 

 kind of balance is to be kept, such as you actually see in 

 organisms. If Jimmie Jones eats all the time and never 

 o-ives up anything, Jimmie would become unwieldly; but 

 this is not all. We know from observation that this 

 continued self-building would defeat its own ends. Jimmie 

 needs, exercise, we say, in order to keep well; but 

 exercise is outgo. It destroys some of this which has been 

 built up. You will find, however, that this alternate 

 building up and tearing down results in a better self than 



