27 215 



sions, and on the view of the wheel-organ advanced above. And il is at all events 

 not -weakened by the fact that, with regard to the biology of the animals, especially 

 with regard to the propagation in the Freshwater-Turbellaria, we find all those phe- 

 nomena again in greater or smaller degree, which govern the propagation of the Roti- 

 fera (heterogoni, parthenogenetic propagation, resting eggs, no larval stages) whereas in 

 the marine Planaria, if present at all, they must be regarded as great exceptions 

 (see v. Graff 1882, p. 145). During recent years several authors especially Gbobben 

 in his "Lehrbuch" and partly Martini (1912, p. 627) have tried by means of the 

 Gastrotricha to connect the Rotifera with the Nematoda. As far as I can see, the struc- 

 ture of the excretory organ and that of the Nematoda present great difficulties for 

 this arrangement. 



As well known, most of the authors before me have maintained, that the deve- 

 lopmental centre of the Rotifera should be looked for in the freshwaters and not 

 in the sea. This is the case with Hudson (1889, p. 437), Daday (1892, p. 95), Lie 

 Petersen (1905, p. 1), de Beauchamp (1909, p. 59), v. Hofsten (1912, p. 163). Only 

 Zelinka (1907, p. 1) has maintained quite the opposite view, asserting that the 

 developmental centre should be looked for in the sea. He has been opposed espe- 

 cialh' by de Beauchamp, and mainly by quite the same arguments as 1 would have 

 used. It is not necessary to go into details upon this point; I refer the reader to the 

 above-named papers, especially those of de Beauchamp and of v. Hofsten. I only 

 wish to add that the authors, as far as I have been able to see, with regard to 

 their conception of the systematical position of the Rotifera have not drawn the con- 

 sistent conclusion from their interpretion of the original home of the Rotifera. 



2. It has been pointed out that upon many essential points de Beauchamp and 

 myself agree in our criticism of the system of Hudson-Gosse. Whereas I draw the 

 inference of the criticism and, working upon it, try to reform the system, de Beau- 

 champ returns to the system of the English authors saying: "le vieux groupement en 

 ordres emprunté à Dujardin et à Hudson demeure le meilleure avec les corrections 

 que nous avons faits" (p. 40). As however the conception of the Notommatidœ as the 

 most primitive of all Rotifer families, the arrangement of the other families in develop- 

 mental lines deriving from them, and the interpretation of the division of Ploima 

 into Lorica and lUoricata as "néfaste", so to speak totally subverts the whole system 

 of HuDSON-GossE, I cannot see that it is scientifically defensible to return to it. 

 When DE Beauchamp says about my system: "Son groupement en ordres et sous- 

 ordres est beaucoup plus contestable" (p. 39) than mj' arrangement of developmental 

 lines, deriving from the Notommatidœ, I fully agree with him. I only take the liberty to 

 add that the system of Hudson-Gosse cannot be regarded as better for that reason. 

 When de Beauchamp is able to return to this system while I am not, this is due 

 to the different starting points of our investigations. He who has based his in- 

 vestigations of the Rotifera upon studies in Nature, and understood how the deve- 

 lopmental lines, starting from the creeping animals and ending in the plancton or- 

 ganisms, have slowly been developed, and further seen how the organisation has 



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