THE STRUGGLE FOB THE LIFE OF OTHERS. 225 



within the sphere of sex it is in the care and nurt 

 ure of the young, in the provision everywhere 

 throughout Nature for the seed and egg, in the 

 endless and infinite self-sacrifices of Maternity, that 

 Altruism finds its main expression. 



That this is the true reading of the work of this 

 second factor appears even in the opening act of 

 Reproduction in the lowest plant or animal. Pledged 

 by the first law of its being the law of self-pres 

 ervation to sustain itself, the organism is at the 

 same moment pledged by the second law to give up 

 itself. Watch one of the humblest unicellular 

 organisms at the time of Reproduction. The cell, 

 when it grows to be a certain size, divides itself into 

 two, and each part sets up an independent life. Why 

 it does so is now known. The protoplasm inside the 

 cell the body as it were needs continually to draw 

 in fresh food. This is secured by a process of 

 imbibition or osmosis through the surrounding wall. 

 But as the cell grows large, there is not wall enough 

 to pass in all the food the far interior needs, for while 

 the bulk increases as the cube of the diameter, the 

 surface increases only as the square. The bulk of the 

 cell, in short, has outrun the absorbing surface ; its 

 hunger has outgrown its satisfactions ; and unless the 

 cell can devise some way of gaining more surface it 

 must starve. Hence the splitting into two smaller 

 cells. There is now more absorbing surface than the 

 two had when combined. When the two smaller cells 

 have grown as large as the original parent, income 

 and expenditure will once more balance. As growth 

 continues, the waste begins to exceed the power of 

 repair and the life of the cell is again threatened, 

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