American Museum of Natural History 



SPECIALIZATION IN VOLVOX 



The cells arranged in a single layer as a hollow sphere are connected with one 

 another by strands of protoplasm. Each cell, with its chlorophyl and vibrating cilia, 

 carries on all the life functions except reproduction. Certain cells within the hollow 

 sphere become segregated: these specialize in reproducing new colonies 



reproduction, exactly the same process in a many-celled plant or animal results 

 merely in growing larger, becoming more. When a many-celled organism 

 produces spores or gametes that we can distinguish from the parent, we can 

 distinguish reproduction from vegetation. Certain cells now arise that cannot 

 continue to grow and divide except as an individual distinct from the parent 

 tissues. Reproduction has become differentiated from vegetation. 



This differentiation of reproduction from vegetation, or of offspring from 

 parent, means that reproduction can become more than replacement. The life 

 of the parent organism, past the point of reproduction, is in a sense a net gain. 



419 



