HELMINTHOLOGY HELMINTHES CYSTICI. 487 



situation in these animals cilia should occur. Owen (Lec- 

 tures on the Comparative Anatomy of the Invertebrata, 

 p. 44) is still unacquainted with the relation in which the 

 progeny of the Eciiiiwcoccus stands with respect to the 

 mother-cyst. He regards the mother-cyst as a distinct 

 genus of the Cystica, in which the two species, Acephalocystis 

 socialis \jprolifera, Cuv.] and eremita (vel sterilis], or 

 endoyena and exoyena, are distinguished. In the former 

 species filial cysts are developed on the internal surface of 

 the mother-cyst by a fissiparous process, whilst in the latter 

 the development of the progeny takes place on the external 

 surface. This latter mode of increase of the Acephalocystis 

 eremita, which is said to occur especially in the Ox and 

 other domestic animals, has never come under the Reporter's 

 observation. Owen also compares the mother-cyst of his 

 Acephalocysts to a " gigantic organic cell/' in which occa- 

 sionally other animals furnished with suctorious acetabula 

 and a coronet of spines, the so-called Echinococci, set up 

 their abode. Thus Owen is not, in this place, aware that 

 these latter are the progeny of the Acephalocyst. He com- 

 pares the Echinococci, moreover, to polygastric infusoria, 

 the retracted coronet of hooks offering in his eyes a close 

 resemblance to the cylinder of teeth of the Nassula [and 

 many other Polvgastria] , and the clear globules (calcareous 

 corpuscles) in the parenchyma of the animals appear to him 

 very similar to the [so-called] stomachs of the Polygastria ; 

 he even thinks that he once observed the little Echinococci 

 in the mother-cyst moving in the fluid, in the manner of the 

 Infusoria, apparently by the action of superficial vibratile 

 cilia; which has certainly been an illusion. Consequently, 

 Owen afterwards looked in vain for any such ciliated epithe- 

 lium in the Echinococci of a small Musk-deer [which he 

 attributes to the Echinococci being dead]. 



According to Rokitansky (Handbuch der pathologischen 

 Anatomic, Bd. ii, pp. 364, 465), who, as for the rest, 

 also speaks of Acephaloc} r sts, the Echinococcus hominis 

 very rarely occurs in the muscles and in the substance 



