224 DESCRIPTIONS OF PREPARATIONS. 



Sinus of vas deferens and the ovarian capsule. Gibbs Bourne, op. cit. p. 473. 

 Spermatophores. Cf. Robin, A. Sc. N. (4) xvii. 1862. 



Nephridia-. of Hirudo, Gibbs Bourne, Q. J. M. xx. 1880; xxii. 1882, p. 337; 

 of other Leeches, Id. Q. J. M. xxiv. 1884, p. 478 ; Schultze, A. M. A. xxii. 1883. 



46. TAPEWORM (Taenia serrata), 



"With the cysts of Cysticercus pisiformis, s. C. Taeniae serratae. 



IN the upper part of this preparation is suspended a portion of the 

 great omentum of a Rabbit (Lepus cimiculus). Seven pyriform sacs may be 

 observed attached to it, a group of three on the left-hand side and a fourth 

 at the right-hand corner being especially conspicuous. These sacs are 

 connective tissue cysts which lodge each a single individual and rarely 

 more of the cystic stage (Cysticercus pisiformis] of T. serrata. See next 

 preparation. The presence of the parasite, like the presence of any other 

 foreign body, has had an irritating effect on the tissues of the omentum, and 

 the consequence is the formation of a protective capsule. The brain and 

 the eye are the only two parts of the body in which this capsule is never 

 formed. 



In the lower part of the preparation is suspended a Tapeworm, Tcenia 

 serrata, which inhabits the intestines of the dog. When a dog devours a 

 rabbit, and swallows an encapsuled Cysticercus pisiformis, the head and 

 neck of the latter develop into the Tapeworm, as it is seen here. The head 

 and neck are displayed in the middle line, bent forwards and downwards. 

 With the aid of a simple lens the head may be seen to possess a slight 

 median projection, the rostellum, at the base of which is a circlet of 

 chitinous hooks. The possession of these hooks constitutes the difference 

 between an ' armed ' and an * unarmed ' Tapeworm. ' Unarmed' Tapeworms 

 are not found in the Carnivora. The head expands below the hooks, and 

 bears four rounded pit-like suckers, one of which is turned towards the 

 observer. It then contracts into a short unjointed neck. The neck begins 

 to broaden out into the body of the worm, and it is at the same time 

 divided by transverse lines into a series of joints. The first joints are 

 almost linear : they then become broader and deeper, and finally their 

 depth becomes greater than their breadth. Their posterior margin be- 

 comes at the same time remarkably prominent. The two last joints are 

 of considerable length and comparative narrowness. They are ripe and 

 ready to be detached. 



If the lateral margins of the joints are attentively examined, one or 

 other is seen to present near its centre a prominent papilla. This papilla is 

 the projecting edge of the porus genitalis. It alternates generally, but not 

 invariably, in succeeding joints from the right to the left side. 



