25 213 



whether the results arrived at in nature, with due consideration to its endless and 

 manifold qualities, have not on the whole, as great a scientific value, even if the 

 results in question appear in a more unostentatious, and less dazzling form. 



The investigations which are commenced and rest upon profound studies in 

 Nature and the results of which are later on subjected to thorough investigations in 

 the laboratories, are those which most promote science. 



As far as I am able to see de Beauchamp agrees with uie in the following main 

 points : We have both arrived at the result, that the Turbclktria may be regarded as 

 the nearest allies of the Rotifera; that the primitive wheel-organ of the Rotifera is 

 a ciliary disc, placed ventrally and encircled by long cilia; that the system of Hud- 

 soN-GossE must upon all essential points be regarded as very unnatural. With re 

 gard to the order Scirtopoda de Beauchamp confesses that Hudson-Gosse "exagérait 

 l'importance" of Pedolion. The division of the Ploïmes in Loricata and llloricata is 

 "néfaste". In contradiction to Hudson-Gosse but in accordance with my views de 

 Beauchamp regards the Notommatidœ as the most primitive of the families; upon 

 my "groupement des families en séries divergentes à partir des Notommatidæ" he 

 says that it has "peu de changements à subir et se retrouve en bonne partie dans 

 le tableau ci-contre (p. 41)". 



On the other hand we disagree upon very essential points, and it is easy to 

 show that this is due to the different mode in which we have studied the great 

 questions in which we have both been interested. 



The three main points are the following: (1) The systematical position of the 

 Rotifera; (2) the different use we make of ou.r criticism of the system Hudson-Gosse, 

 and (3) the systematical arrangement of some of the families. 



1. Even if de Beauchamp is like myself inclined to see in the Tuibellaria the 

 nearest allies of the Rotifera, he also believes he can find affinities with the Gephyrea, 

 the Brachiopoda, the Axobranchia and quite especiallj' with the Mollusca. I shall not here 

 enter into detail with regard to the discussion of the affinities with these groups, 

 but only paj' attention to one point which I think has hitherto been rather over- 

 looked. 



In contradiction almost to all other great divisions of the animal kingdom which 

 are bound to fresh water, the fresh waters seem to be the real home of the Rotifera, 

 the element in which the group originated. What characterizes the freshwater fauna 

 is, that it is an emigrant fauna, either deriving from the sea or from the land, a 

 fauna of emigrants, the home of which was originally to be found everywhere, not 

 only in the element in which it lives nowadays, i. e. in the freshwater itself. Owing 

 to the peculiar conservatory power of the freshwater with regard to all types of 

 animals which, from the oldest epochs of the earth and to our own day, escape 

 into it, the freshwater fauna is a relict fauna, to which the oldest prehistoric oceans, 

 as well as our present ones have provided and still provide their contingents. We 

 are not for a moment in doubt that the developmental centres, with regard to Bvijozoa, 

 Spongia, Crustacea, Coelentera, Insecta, Mollusca, Fishes, have never Iain in the fresh- 



D. K. D. Vidensk. Selsk. Skr., naturv. og mathem. Afd., 8. Række, IV. 3. 29 



