ECHINOCOCCUS SCOLICIPARIENS. 197 



towards the stalk, a circlet of 30 34 hooks, in a double series, 

 shines through, and from its anterior extremity the four sucking 

 discs appear in the same way (as Wedl has correctly per- 

 ceived and figured, and as Eschricht supposed, but, as he says, 

 did not actually see), and in these discs the well-known roundish 

 calcareous corpuscles, measuring O'Ol 0*02 millim., are imbedded 

 (vide infra). If the Echinococci be left uncovered to roll about 

 upon the field of vision, we see that, as Eschricht states, they are 

 not really round vesicles, but flat discs (or depressed sacs), on 

 one surface of which, towards the anterior portion, there is a 

 blunt elevation. These scolices of Echinococcus are the ana- 

 logues of those structures M-hich Van Beneden has figured on 

 pi. viii of his work already quoted, and in other places; so that in 

 speaking of the individual scolices we can hardly call them 

 cystic worms. 



The calcareous corpuscles have but slightly marked sides and 

 angles, and rather a round, cellular appearance. Eschricht, who 

 thought he saw a nucleus in them, has probably been deceived, 

 either by the deposition of the calcareous matter in concentric 

 layers, as is sometimes the case, or by the glimmering of a 

 small corpuscle through a larger one behind which it lay. He 

 thinks also, that although the calcareous corpuscles occur in 

 various parts of the skin, they have, nevertheless, a certain regu- 

 larity in their distribution. Thus they form a distinct circle 

 close to the outline of the body, another round the hooks, and a 

 series along the middle line, whilst a lighter space occurs between 

 the poles and the circlet of hooks, that is to say, about the posi- 

 tion of the sucking discs, the neighbourhood of which is generally 

 free from a deposition of calcareous corpuscles. I can confirm 

 these latter statements from particular cases of Echinococci 

 in animals, but here I rarely saw it in this manner. The 

 number of calcareous corpuscles which Eschricht, however, 

 regards as cells containing silica is often small, and often much 

 larger, as for instance, more than a hundred in one individual. 

 The younger an individual is the smaller and less distinct are the 

 corpuscles, and the fewer of them are there in the animal ; the 

 older it is, the more abundant are the corpuscles. The size of the 

 hooks, according to Eschricht, is O02 O022 millim., or about 

 O'Ol'", a statement which, as we shall show further on, is not 

 quite correct, as the hooks of the first and second series vary 

 amongst themselves. 



