54 ILLINOIS BIOLOGICAL MONOGRAPHS [174 



Development of the testes in the male proceeds as described for Gordius 

 robustus. The membranes enclosing the testes are usually not so heavy as 

 in that species and the cellular parts of the sperm ducts extend both anterior 

 and posterior to the short muscular areas. 



The spermatozoa develop as in the previous species except that the 

 head and cytoplasmic parts become more definitely separated before the 

 axis of the cell becomes straightened, causing the spermatozoon to be 

 doubled upon itself when it is first formed (Fig. 137). Head and cytoplas- 

 mic part are definitely separated from each other. In the seminal receptacle 

 of the female the cytoplasm elongates into the heavy flagellum of uniform 

 diameter (Fig. 138). 



, The reproductive organs in the female develop very much as they do in 

 Gordius robustus. The membranes forming the primary ovarian tubes are 

 not so heavy as in that species. The cloacal structures arise essentially as 

 in Gordius robustus, but show modifications in certain details. 



The part of the cloaca lined by the invaginated hjrpoderm forms a tube 

 at the posterior end of the body equal in length to at least twenty times 

 the diameter of the body at that point. The intestinal diverticula arise 

 a short distance anterior to the point of union between ectoderm and 

 entoderm and are less distinct than in Gordius robustus, appearing only 

 as the points at which the intestinal wall begins to become modified. 

 The oviducts develop from the posterior ends of the primary ovarian tubes 

 and unite to form the rudiment of the cloacal gland and seminal receptacle 

 The receptaculum seminis becomes distinctly separated from the gland, 

 remaining connected by a narrow neck (Fig. 168). The ovaries open at 

 the sides into the anterior end of the gland and the intestine opens into it 

 on the dorsal side at the posterior end, or perhaps it would be more correct 

 to say in this case that the gland opens into the ventral side of the intestine. 

 (Figs. 168, 171). 



At the point of union between entoderm and ectoderm a constriction 

 or valve appears in later stages (Fig. 171). The inner ends of the cells 

 lining the cloaca between the valve and the cloacal gland secrete a 

 clear substance that almost completely fills the lumen of the tube. 

 A similar substance is secreted by the cells lining the oviducts. Radiating 

 from the cells are thin membranes apparently enclosing the substance, 

 and a heavier layer surrounds the remnant of the lumen. In the adult 

 stage the inner part of the secretion is swept away and little remains 

 except the bases of the membranes which Montgomery regarded as cilia. 

 The hypoderm of the posterior region of the cloaca also secretes a hyaline 

 substance which passes in long threads thru cuticular pores into the lumen 

 (Figs. 7, 171). This substance disappears at the time of the entrance 

 of the spermatozoa and may aid in their migration into the seminal recep- 

 tacle, but the secretion of the substance continues after insemination. 



