1910] Johnson: Quantitative Study of Salpa Chain. 17.") 



smaller at each end of the block, and the maximum size occurs 

 near, but not at the distal end. 



16. These results suggest that farther investigation may show 

 the graph of the block to be a reliable species character. 



17. A stalk of Equisetum robustum lias shorter internodes al 

 the base and at the tip, the maximum ones occur near the base. 

 The diameter of the internodes is least at each end and greatesl 

 in the middle. 



IS. An unusually small zooid is often found opposite an un- 

 usually large one in the salpa chain. 



The conclusions reached of a- more general, or theoretical 

 character, are : 



1. The periodicity occurring in the salpa chain may be a phe- 

 nomenon comparable with the grand period of growth and also 

 with the length period of the internodes, as defined by botanists. 



2. Dr. Pearl's first law of growth finds a parallel for the 

 salpa chain, since the size of a zooid is a function of its position 

 in the block. 



