244 CYSTICERCOOIDS PARASITIC 



imate length of this appendage is the twenty-third of an inch. 

 At its point of attachment to the concavity of the shell it is very 

 narrow, but gradually becomes broader as it approaches the groove 

 or foramen of the cyst. Its contents consist of a cellular sub- 

 stance, whose nuclei readily stain under the influence of picro- 

 carmine. 



The inner wall of the cyst is lined with a thin, transparent 

 membrane or epithelium. Between this epithelium and the mem- 

 brane which encloses the embryonic head is a watery secretion. 

 It is very rare to find any movement going on within the cyst. 

 There have been times when I have noticed an oscillation, but it 

 has not been very perceptible. The cuticle at the point of invagi- 

 nation closes up, forming a cone, so that it is difficult to find an 

 orifice if one really exists. I have been unable up to the present 

 time to find any trace of the original six hooks of the embryo, 

 which must have previously existed, on any part of the structure 

 of the cyst or the ribbon-like appendage. 



On examining the Cysticercooids when freed from their host, 

 there are but faint outlines of the rudimentary head, suckers, or 

 rostrum, the circlet of hooks being the most prominent part of the 

 whole mass. If the cyst is crushed between a slip and cover- 

 glass, or under the compressor, we cannot force out the contents 

 through the invaginated end, as one would imagine if there was 

 an aperture in that portion of the cyst ; but it usually becomes 

 ruptured on one side, and the contents, together with the circlet 

 of hooks, are forced out through the ruptured wall of the cyst. 

 Under such circumstances the emitted contents have a plasma-like 

 appearance, bounded by the membrane, and with but faint 

 outlines to indicate the presence of a taenia head. With a view of 

 perfecting the scolex, I tried some feeding experiments on rats and 

 mice, both tame and wild, but by 2, post-mortem examination I was 

 unable to trace them. Steeping the cysticercus in warm water, as 

 Leuckart recommends in the case of C. arionis^ was useless, so 

 recourse was had to other means. Steeping them in hydrochloric 

 or acetic acid, either cold or warm, did not give good results, so I 

 tried nitric acid, in the first place cold, steeping them for about 

 ten minutes. The contents became more defined, and on rup- 

 turing them whilst in the fluid, the expelled contents became 



