310 DR. T. S. COBBOLD OK SCLEEOSTOMA STNGAMUS. 



escape, seeing that the vagina is blocked up by the intromittent 

 organ and bursa of the male ? Clearly the eggs can only escape by 

 an eventual breaking up of the body of the parent ; this result, 

 however, is quite admissible, as it constantly happens in the ces- 

 tode proglottides, where the vaginal orifice is too small to allow 

 of the escape of the eggs vrith their contained six-hooked embryos. 

 The eggs of Sclerostoma Syngamus are comparatively large, mea- 

 suring longitudinally as much as the a-y-g-th of an inch, their trans- 

 verse diameter being just half the above measiirement ; the length 

 of the yelk is g^^o^h from pole to pole. The process of segmentation 

 of the yelk accords with that observable in nematodes generally, 

 the spherical cellules represented in the accompanying drawing 

 (fig. 5) averaging a breadth of only ^ /q g th of an inch. The egg itself 

 is oval, and bordered by two extremely delicate and transparent 

 envelopes, whose curvatures at either pole are slightly interrupted, 

 and the eggs consequently present truncated ends when viewed 

 in profile. Many of the ova contain fully formed embryos ; and 

 in the centre of the lower third of the body of one of them I 

 distinctly perceived an undulating canal, probably constituting the 

 as yet imperfectly formed intestinal tube. By whatever mode the 

 young make their exit from the shell, it is manifest that prior to 

 their exptdsion, they are sufficiently developed to undertake an 

 active migration. Their next habitation may occur within the 

 body of certain insect larvae or even small land mollusks ; but I 

 think it more likely that they either enter the substance of vege- 

 table matters or bury themselves in the soil at a short distance 

 from the surface. 



Finally, I propose very briefly to notice the various methods 

 which may be adopted with the view, on the one hand, of checking 

 the destructive influences of this parasite, and, on the other, of 

 limiting its abundance. 



First. When the worm has taken up its abode in the trachea 

 of fowls and other domesticated birds, the simplest plan consists, 

 as Dr. Wiesenthal long ago pointed out, in stripping a feather 

 from the tube to near the narrow end of the shaft, leaving only a 

 few uninjured webs at the tip. The bird being secured, the webbed 

 extremity of the feather is introduced into the windpipe. It is 

 then twisted round a few times and withdrawn, when it will usually 

 happen that several of the worms are found attached. In some 

 instances this plan entirely succeeds ; but it is not altogether 

 satisfactory, as it occasionally fails to dislodge aU the occupants. 



Secondly. The above method is rendered more effectual when 



