68 ILLINOIS BIOLOGICAL MONOGRAPHS [188 



Paragordius varius some of the eggs are retained in these tubes and later 

 pass back along them to the oviducts, but the majority of eggs are contained 

 in the ovarian buds and are liberated by the rupture of the membranes, 

 pass back along the tubes formed by the parenchymatous walls which 

 form the mesenteries, and enter the oviducts when they reach the posterior 

 end. In Gordius robustus no eggs are retained in the primary ovarian tubes 

 and all pass back along the body cavity. It is evident from the descrip- 

 tions given in this report that the only name applicable to either a primary 

 ovarian tube or the ovarian buds or both together is ovary. 



The budding of the ovaries, which by Vejdovsky and Svabenik was 

 regarded as rudimentary body metamerism, was found in the species 

 examined to be highly irregular and not opposite in the two ovaries. Con- 

 sequently it can be regarded as no more of an indication of true metamerism 

 than the branching of the intestine in the polyclads or of the uterus in some 

 of the larger cestodes. 



PHYSIOLOGY 



The functions of the organs in the Gordiacea are practically unknown. 

 Interpretations have usually been made from analogy with similar organs 

 in other groups, rather than from actual observations. But in an isolated 

 group like that of the Gordiacea such interpretations are very unreliable. 

 In the present investigations certain observations have some bearing on 

 the possible functions of some of the organs and the interpretations are 

 given here more as possibilities than as certainties. 



Nutrition. The absorption of nutritive substances seems to be carried on 

 by the entire outer body surface. In the younger stages of Gordius robustus 

 the hypoderm cells appear also to secrete a digestive substance that attacks 

 the cells of the surrounding tissues of the host. Thus the young specimens 

 enclosed in the tissues of the hosts in the later stages are always found in 

 larger pockets formed by the digestion of the cells immediately surround- 

 ing the parasite. The digestion does not appear to take place at any one 

 point of the body of the parasite, but occurs simultaneously at all points. 

 In later stages even in Paragordius varius it seems impossible that any 

 capillary tube that may form the anterior opening of the intestine could 

 supply a large enough quantity of fluid from the body cavity of the host 

 to feed the developing parasite. In Gordius robustus that is entirely out 

 of the question, as in that species there is clearly no anterior opening to 

 the intestine. 



Excretion. The conclusion that the hypoderm and not the intestine 

 carries out digestive functions in the parasite leaves the high stage of 

 development of the intestine entirely unexplained. It is, however, not 

 necessary to look far for the probable function of the intestine. It fulfils 

 every requirement of an excretory tube. The resemblance of its structure to 

 that of the Malpighian tubules in insects is very close, as I had sufficient 



