THE CONSERVATION OF LIFE 247 



Bat what becomes of the old maternal organism ? When all 

 germ-cells have seceded it continues to exist for some time but 

 is unable to form new germ-cells, for body-cells can only produce 

 body-cells. Soon symptoms of old age become perceptible ; one 

 function after the other ceases, and finally the colony reaches 

 the inevitable end and dies. For the first time in the organic 

 world we see here that death appears as a physiological necessity, 

 as the inexorable fate which is henceforward in store for all 

 organisms after a shorter or longer existence. Of what benefit 

 would continued life be to the unfertile Volvox ? It would be 

 useless for the preservation of the species, and at the best 

 handicap the course of life for the young colonies. But Nature, 

 as we have seen on various occasions, has no regard whatever 

 for the individual and will waste billions of life germs, to achieve 

 its only object : the preservation of the species. 



But why must the Volvox die? Why was it necessary for 

 death to come into the organic world ? 



We are confronted here for the first time with a new difficulty. 

 How is it possible for the germ-cells to develop into a complete 

 Volvox colony? Owing to which qualities are they able to 

 reproduce not only their like, but also body-cells which are widely 

 differentiated in structure ? It is the great problem of heredity 

 which here unrolls itself before us. That both parts of the 

 amoeba develop into organisms which are like the mother we 

 seem to understand without any difficulty, for here no develop- 

 ment is required, only simple growth, because progeny and 

 progenitor are morphologically equivalent from ' birth.' But 

 it is already different in the Infusorians. Here both descendants 

 must by new-formation generate the organella of which they 

 were deprived during fission. It is therefore clear that the 

 infusorium must have inherited from the mother the faculty to 

 develop all the individual parts of its body out of itself. But I 

 must leave the problem of heredity for a later occasion when we 

 come to consider the various theories of heredity. 



If a colonist, a second Eobinson Crusoe, should reach a 

 strange, uninhabited land, fertile as the Garden of Eden, and find 

 everywhere identical favourable conditions of existence he will 

 not be long in doubt where to choose his future homestead. 

 Wherever he happens to be he will erect his hut. As Nature 



