118 QUANTITATIVE PLANKTON INVESTIGATIONS [PART II 



anatomist. Collections of animals from all parts of the world 

 were made and described, and the species so obtained were named 

 and classified. The names of a whole army of workers will occur 

 to the student in this connection. The older human anatomists 

 were they who concerned themselves with the structure of animals 

 other than man : such were John Hunter, the three Monros and 

 many others. When however the conception of evolution, as the 

 result of processes of natural election, became generally accepted 

 then the study of morphology became the fashion, and zoologists 

 sought in the results of comparative anatomy and embryology the 

 keys to the inter-relationships of the great groups of animals ; 

 Anton Dohrn and Huxley set this fashion. But the field of phylo- 

 genetic speculation was destined to prove a somewhat sterile one, 

 and it has to be confessed that the study of such things as gill- 

 slits, coelomic cavities and the like, has not afforded the results 

 that were expected. In recent times it has become recognised 

 that the older methods of morphology are alone inadequate for 

 the solution of the question of the historical development of 

 animals, and we have attacked this question on the one hand 

 from the point of view of palaeontology, and on the other by 

 statistical and physiological methods of inquiry. 



The study of variation began with Darwin. But during the 

 last two or three decades the variability of animal structures has 

 been studied mathematically by Karl Pearson, Galton, Heincke, 

 Duncker and others, and this branch of zoology, biometrics, has been 

 developed to a very great extent. The rediscovery of Mendel's 

 laws of inheritance led also to the development of quantitative 

 biological methods. The results of the oceanographical voyages 

 had the same effect. This science originally concerned itself with 

 the determination of the areas, depths, currents, and the physics 

 and chemistry of the oceans. But soon biological and oceano- 

 graphical investigations were carried on concurrentl}^ and it was 

 found that much was to be learned from the consideration of the 

 occurrence of marine organisms in relation to the physical and 

 chemical conditions of the sea areas in which they were to be 

 found. This led to the attempt to investigate the distribution of 

 animals as far as possible in a quantitative manner. But there were 

 very great difiiculties in the way of investigating the distribution 



