Division of Labor 85 



most primitive living things carry on the same essential func- 

 tions as the " highest " or most complex and elaborate — the 

 special organs characteristic of the latter being entirely lack- 

 ing in the former. To show that function precedes structure 

 in the history of life upon the earth, we should have to show 

 that as a matter of chronology the simplest plants and ani- 

 mals made their appearance before the more complex ones. 

 This has already been discussed in connection with the records 

 disclosed by the fossil-bearing rocks (page 48) . 



To many the statement that function precedes struc- 

 ture will seem like saying that there was cutting before there 

 were knives, or that there was killing before there were 

 weapons. No matter how crude a tool or a weapon the 

 savage of the early stone age fashioned out of a random stone, 

 the instrument is there in advance of its operation. In the 

 same way, the ameba does in fact carry on its functions by 

 means of existing structural mechanisms, which we may, if 

 we wish, properly consider as organs. Nevertheless, the dis- 

 tinction is important if we are to understand the evolution- 

 ary implications of the facts. The lowest stage shows us a 

 body of seemingly undifferentiated protoplasm performing 

 each and every function of living. From similar protoplasm 

 we later see emerge specialized structures that seem almost to 

 have lost the common characteristics of bare " protoplasm." 



It may be helpful to reflect that in the history of human 

 culture clothing was made before there were any tailors, food 

 was cooked before there were any cooks, shelters were con- 

 structed long before there were architects, builders or 

 contractors. 



Division of Labor 



In fresh-water ponds and in the ocean are found tiny 

 animals that appear to be hardly more than hollow sacks 

 (Fig. 20). The cells of the inner layer, chiefly food- 

 preparers, are protected by those of the outer layer. Some of 

 the external and some of th^ inner layer cells have extensions 



