CHAPTER II. 



Contributions to our knowledge of the natural system 



of the Ostracods. 



Some Liuroductori, Duriiig the course of the last ceutiuy zoological classification has, as we know, — like 



remarhs. |.j^g biological sciences in general — shown an enormous advance. The cause of this is probably 



to be found especially in the way in which the idea of evolution has asserted itself in biology. 

 The purely descriptive classification, whose main — and in many cases only — object was to try 

 to get an arrangement and summary of the multitude of forms belonging to organic life, has 

 given way to deeper and more scientific efforts. Natural scientists have laid down as their 

 object an attempt to establish, by means of comparison, the laws of the phenomena in the 

 animal and vegetable kingdoms and an attempt to arrive at an understanding of these pheno- 

 mena by means of exact methods and experiments. 



It is true that even C. v. LiNNE spoke about ,, natural" and ,, artificial" systems, but 

 it was only after the theory of evolution was put forth that the idea arose that a real consan- 

 guinity existed between the different systematic categories. The motto was formulated that 

 ,,the degree of resemblance is a measure of consanguinity; the greater the resemblance is, the 

 closer are the genealogical bonds, the greater the difference becomes, the farther away is the 

 common original form". 



During the first decades after Darwin's epoch-making work ,,0 n the Origin of 

 Species". 1859, the main interest of zoologists was directed to comparative morphology 

 and embryology; they tried to obtain from these departments of study facts that might explain 

 the genetic position of the difi'erent groups of animals. But it was the great increase of interest 

 in the field of tli(>oretical speculation as to evolution that probably left the greatest impression 

 on this period f)f investigation. Both experts and laymen often devoted themselves freely to 

 far-reaching speculations, hypotheses were often constructed on hypotheses, facts were often 

 made to fit in with hypotheses previously arrived at. During this time the ..pedigree" of the 

 animal world was constructed and tlic liypotJietical original forms of tlie difi'erent groups were 

 re-conatructed. 



