64 ILLINOIS BIOLOGICAL MONOGRAPHS [184 



than in Paragordius varius. The brown gland which he found in the region 

 of the esophagus is either homologous with the part of the larval esophagus 

 of Paragordius varius that grows over the intestine or else is homologous 

 with the anterior glandular part of the intestine itself. The latter has been 

 the opinion of Montgomery and others who have studied the larva. From 

 the present investigations it is evident that the mouth does not become 

 open until the adult stage is reached. In Gordius it never becomes open; 

 for the connection between the larval esophagus and the intestine is severed 

 at the very beginning of the parasitic stage and no opening can be present 

 after that. It was upon examination of sections of Gordius rohustus that 

 Ward (1892) made the positive assertion that in the specimen examined 

 there was no trace of an esophagus. Others have obtained similar results 

 in this and related species. Thus Rauther in the form he designated as 

 Gordius aquaticus states that he still finds the mouth opening as a thin 



V 



chitinous tube, but fails to find any trace of an esophagus, Svabenik states 

 that in Gordius montenegrinus the alimentary canal is very degenerate. 

 Both of these species are very closely related to Gordius rohustus. 



There is a regression in the cells of the alimentary canal when the adult 

 stage is reached, but it is not much more pronounced than the regression 

 that begins at the same time in the other tissues. 



The cilia mentioned in the cloaca and genital tubes in the reports of 

 Montgomery and Rauther have been explained in the description of Para- 

 gordius varius. Rauther also figures cilia for the intestine of Gordius tolo- 

 sanus. His description, however, explains his error. He states: "In der 

 kaudalen Darmregion von G. tolosanus war auch deutlich zu beobachten, 

 dass die freie innere Oberflache des Epithels einen sehr regelmassigen 

 fibrillar struirten Saum tragt, der offenbar aus kurzen Cilien besteht." 

 What he observed was nothing more than the inner differentiated zone 

 that was in some cases found in Gordius rohustus in the present investiga- 

 tion. It is this type of theoretical interpretation found everywhere in 

 Rauther's paper that makes his conclusions almost worthless. Fortunately 

 he has usually given his actual observations before interpreting them. 

 I have found no ciUa in the intestine of either of the species studied in any 

 stage of development. 



Another case of Rauther's interpretation is his defense of Vejdovsky's 

 statement that the male cloaca is evertable and serves as a bursa copula- 

 trix. He defended Vejdovsky's statement in an attempt to explain the 

 bristles around the anus of the male, in spite of the fact that he knew that 

 it had been contradicted by Camerano, von Linstow and Villot, and that 

 he had observed no evidence to prove its correctness. But, the figure 

 given by Vejdovsky (1886, Fig. 31) shows conclusively that the structure 

 at the anal opening can not possibly be the everted cloaca. He shows the 

 cloaca still in place and the cellular part ending at the anus. The part 

 extruded was evidently a mass of spermatozoa. 



