author's abstract op this paper issued 



BY the bibliographic SERVICE, MARCH 20 



ON THE RESPIRATION OF DYTISCUS MARGINALIS L. 



H. C. VAN DER HEYDE 



Physiological Laboratoi'ij of the Free University in Amsterdam, Holland 



THREE FIGURES 



For a comparative physiologist fresh water is the best medium 

 from which to gather his material. It is, as Professor Jordan^ 

 pointed out, very poor with regard to its more highly organized 

 primitive forms. Nearly all representatives of those groups 

 which are called 'high' in the scale of phylogenesis of the mor- 

 phologists and systematists, especially the insects, prove by 

 their structure that doubtlessly they originally inhabited the 

 land. As the structure of an organism is determined on one 

 side by its phylogenesis, but on the other hand by the claims of 

 'Milieu' and 'Umwelt, ' we may expect that this change of sur- 

 roundings has caused certain morphological and physiological 

 peculiarities which we are accustomed to call phenomena of 

 'adaptation' or better perhaps of 'being adapted.' Without 

 trying to give an explanation of these phenomena, it is the task 

 of the comparative physiologist to state them and to study them 

 with all applicable methods. Then it will be of special interest 

 to see how far a certain species has emancipated itself from its 

 original environment and how the same problem has been solved 

 in quite a different way in related groups of animals, when we 

 compare, for instance, Dytiscus and Hydrophilus with regard 

 to their respiration in the groups of the Adephaga and the Poly- 

 phaga. 



The respiration of Dytiscus has already been studied by numer- 

 ous investigators, though mostly from the morphological stand- 

 point. In this paper I shall mention some experiments which 

 seem to throw a new light on the whole problem. 



1 Prof. Dr. H. J. Jordan. Het leven der dieren in het zoete water. Utrecht. 

 Oosthoek, 1918. 



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