PART II. 



QUANTITATIVE MARINE BIOLOGY. 



CHAPTER VI. 



QUANTITATIVE PLANKTON INVESTIGATIONS. 



Marine biology is one of the last of the sciences that has 

 adopted quantitative methods. This is not because the study of 

 natural history is an unprogressive one, but just because an 

 enormous mass of descriptive work had to be done before the exact 

 methods of physical and mathematical science could be applied to 

 the solution of problems of a general nature in marine biology. 

 There are probably ten thousand species of fishes which inhabit the 

 seas and fresh waters of the earth, and the fishes are only a group 

 of the vertebrata, while the latter form only one of the smaller 

 sub-kingdoms of animals. All the many hundreds of thousands of 

 animals had to be collected, described and named; and as many as 

 possible of their life-histories had to be investigated before it was 

 possible to attempt any research into the inter-relationships of the 

 different groups. Now all this work was comparative. There are 

 no absolute standards of structure or relationship, and so it has not 

 been possible, until very lately, to deal quantitatively with specific 

 or morphological characters. 



Then we have had fashions in zoological investigation. Prior 

 to the publication of the Origin of Species the methods of 

 natural history were, on the one hand, those of the collector and 

 systematist, and on the other, the methods of the comparative 



