THE FOUR LAWS OF AGE 231 



If it be true that there is among protozoa, among 

 unicellular animals, anything comparable to the 

 gradual decline in the growth power which occurs 

 in us, we shall expect it to be revealed in the con- 

 dition of the cells to see in those cells which are old 

 an increase in the proportion and in the differentiation 

 of their protoplasm, and consequently a diminution in 

 the relative amount of nucleus. That subject is now 

 being investigated, and we shall probably know, within 

 a few years at least, something positive in this direc- 

 tion. At present we are reduced to posing our 

 question. We must wait patiently for the answer. 



The scientific man has many occasions for patience. 

 He has to make his investigations rather where he 

 can than where he would like to. Certain things are 

 accessible to our instruments and methods of research 

 at the present time, but other things are entirely 

 hidden from us and inaccessible at the present. We 

 are indeed, more perhaps than people in any other 

 profession of life, the slaves of opportunity. We 

 must do what we can in the way of research, not 

 always that which we should like most to do. Per- 

 haps a time will come when many of the questions 

 connected with the problems of growing old, which 

 we can now put, will be answered, because oppor- 

 tunities which we have not now will exist then. 

 Scientific research offers to its devotees some of the 

 purest delights which life can bring. The investigator 

 is a creator. Where there was nothing he brings 

 forth something. Out of the void and the dark, he 



