31 



longing to the class of mixed protein substances, and 

 is nearly allied to chitine, but dissolves, when boiled 

 in caustic alkalies, rather more easily than the latter. 

 No re-action of cellulose follows upon the addition of 

 iodine (Kiichenmeister). 



This form corresponds to the second stage of the 

 developmental process of the parasite, the scolex. 



Habitat. Its habitation is various, being found in 

 the muscles (Werner et alii), in the liver (Dupuytren, 

 Leuckart, Laennec), in the heart (Morgagni, Rudolphi, 

 Bouillaud, Andral, et alii), in the choroid plexus 

 (Treutler, Brera, Fischer), in the brain (Ruysch, 

 Chomel, et alii), in the anterior and posterior cham- 

 bers of the eye (Soemmermg, Von Graefe), in the 

 vitreous humor ; in and under the retina (Von GraefeJ, 

 between the sclerotic and conjunctiva (Von Siebold et 

 alii), and in one instance in bone, the first phalanx of 

 index finger (Stanley). When in the closed cavities 

 of the body, e.g., in the ventricles of the brain and in 

 the eye, the Cysticercus lives free ; in other parts of 

 the body, it is surrounded by a cyst, formed from the 

 tissues of the body in which the parasite takes up its 

 abode. 



^Echinococci. 



We now pass to the consideration of the second 

 class, viz., the Echinococci (PL III. figs. 1 and 2). 

 These parasites are contained in a capsule (the 

 hydatid cyst of authors), varying in size from a grain 

 of mustard to that of a hen's egg or more, and of a 

 globular, ovoid, or pyriform shape. Within this ex- 



