28 ILLINOIS BIOLOGICAL MONOGRAPHS [238 



the apex gives rise to the idea that there is a pore here.* I am of the 

 opinion that there is no pore but that the epimerite severs its connection 

 with the trophozoite by gradual constriction at its short neck and drops 

 off as a ball. The apex of the protomerite closes over completely, leav- 

 ing a trace of the narrow channel in the epicyte by which the endoplasm 

 of the two parts was in connection. That there is an opening to the ex- 

 terior at this point in the sporont seems doubtful for I have never seen 

 the extrusion of endoplasm in a freshly taken sporont to which slight 

 pressure was applied; it occurred only when the animal had been kept 

 on a slide in a normal saline or water medium, and then only after from 

 fifteen minutes to an hour, or until the decrease in the density of the 

 outside medium had had time to affect the parasite. 



Not all protomerites of the Stenophoridae are conical in shape. In 

 Stenophora hrolemanni Leger and Duboscq (Fig. 13) the protomerite is 

 shaped like a flattened cork fitting into the neck of a bottle, the deuto- 

 merite surrounding it in a thin layer nearly to the apex; in Stenophora 

 spiroholi Crawley it is almost hemispherical in shape (Fig. 70). 



In sporonts of the Stenophoridae I have seen, the deutomerite is 

 long and slender. Leger and Duboscq record dimorphism in several 

 species, Stenophora silene (Figs. 22, 23), S. chordeume (Figs, 24, 25), 

 S. varians (Figs. 16, 17), etc., wherein the sporonts are both elongate 

 and subglobular in shape. However, I have not observed an authentic 

 and unquestionable case of dimorphism. The long, slender sporonts are, 

 nevertheless, able to contract so as to be of quite a different shape from 

 the normal. Immature specimens of several species are subglobular and 

 stain more deeply than the sporonts but no mature subglobular speci- 

 mens have been seen. 



There is generally a constriction at the septum which distinctly dif- 

 ferentiates protomerite and deutomerite; this is lacking in Stenophora 

 spiroholi Crawley (Fig. 70) and in S. roiusta EUis (Fig. 26), and is 

 only slightly developed in S. polydesmi (Lankester). The widest 

 part of the deutomerite is generally the anterior third; sometimes the 

 deutomerite is a cylinder more or less equal in width throughout. A 

 combination of the two shapes is seen in Stenophora diplocorpa (Fig. 

 21), in which the deutomerite gradually broadens and then contracts 

 in the anterior half, being conspicuously constricted at the middle and 

 cylindrical posterior to the constriction. The deutomerite terminates 

 in a broadly rounded, truncated, or conical extremity. 



The protomerite and deutomerite differ greatly in endoplasmic 

 content, and therefore in color and consistency. The protomerite is 



*As stated by Ellis (1912b) in the Diplopoda. 



