98 ANIMAL PARASITES. 



with ova ; the lateral margins are flatter and whiter. In the 

 latter, Eschricht describes seven layers 1 . Skin. 2. Ventral 

 granular layer, or, more properly, calcareous granular layer. 

 3. Parenchymatous, transparent layer. 4. Central granular layer, 

 also consisting of nothing but calcareous corpuscles. 5. Repeti- 

 tion of layer 3 ; 6, of layer 2 ; and 7, of layer 1, on the dorsal 

 side. 



When Eschricht speaks of only four layers in the central 

 parts, this is no essential difference of structure, but he can only 

 mean thereby that on these parte the calcareous granular layers 

 (as above, layers 2, 4, and 6) are wanting ; these are incorrectly 

 described by Eschricht as nutritive organs, under the denomina- 

 tion of smallest granules (O001 5"' in diameter) and nuclear 

 bodies (0-0075 0-012'" in length and 0-007 010'" in breadth). 

 "We may easily convince ourselves of the calcareous nature of 

 these bodies by treating them with acetic acid, in which they 

 dissolve with effervescence, whilst they remain unchanged in 

 alkalies. Moreover, Eschricht has given up his previous opinion, 

 but still appears to think that the calcareous corpuscles of the 

 Cestoidea contain silica, although I cannot find the chemical 

 reasons for this supposition in his works. As a matter of detail 

 it is to be observed that the skin is divided into a cuticle and 

 corium, that it is inverted at the generative openings, and 

 sprinkled throughout sparingly with calcareous corpuscles, which 

 are abundant in the neighbourhood of the pori genitales and on 

 the hinder margins of the segments. These have been taken by 

 many authors for cutaneous glands (folliculi compositi). A por- 

 tion of the so-called cutaneous follicles may also have been loose 

 terminations of certain parts of the sexual apparatus (vide supra). 

 The parenchymatous layer exhibits contractile cellular tissue 

 (organized sarcode), which consists of threads running at right 

 angles, forming a wide network, and interrupted by the deposi- 

 tion of the calcareous corpuscles, and contains very weak trans- 

 verse and stronger longitudinal muscular stria3, which, however, 

 are less dense than in the Tcenice. 



Vascular system. Whoever has an opportunity of examining 

 my fresh specimens, will certainly find, as in all Cestoidea, those 

 lateral longitudinal cords, which, as is well known, contain a 

 limpid fluid. What network this vascular system may form, we 

 cannot tell at present. Unfortunately, we have no means of 

 rendering these vessels again apparent in spirit specimens, or of 



