NATURE OF THE CALCAREOUS BODIES. 



281 



They are not, however, exclusively confined to the cortical sheath, 

 but are also to be found in the 

 middle layer, only sparsely, 

 however, in the mature joints, 

 though indeed in considerable 

 numbers before the develop- 

 ment of the sexual organs. We 

 must also note that their 

 number varies not only in indi- 



FiG. 144. — Cross section o£ Tcenia solium, 

 showing middle and cortical layers, under low 

 power. 



vidual cases but in the different species, and this to such an extent 

 that one sometimes looks for them almost in vain, while in other 

 cases they are present in extraordinary abundance. 



In the Bothriadse, as we shall afterwards see, the cortical layer 

 also includes the numerous cell-groups which form the yolk-glands 

 (Eschricht's ventral and dorsal granules). 



The connective tissue nature of the ground substance has been 

 recognised on all hands since the publication of my researches in the 

 first edition of this work. Opinions differ, however, as to its exact 

 histological structure. I still maintain that it partakes of the nature 

 of cellular connective tissue. The cells are indeed seldom provided 

 with a distinct cell membrane, in fact they are usually mere nucleated 

 masses of clear protoplasm, and sometimes (especially in the ripe 

 joints) are fused together into a mass, leaving only their nuclei 

 distinct. But these characters not unfrequently occur in connective 

 tissue. In other cases one can observe a distinct intercellular 

 substance usually in the form of a tolerably well-defined cubical 

 network of bands and fibres, with cells of various sizes (up to O'Ol 

 mm.) lying in the meshes. Here and there the nuclei are so closely 

 appressed to the intercellular substance that one can easily mistake 

 the fibres for processes of special cells. There are, indeed, in the 

 parenchyma of the Cestodes true fibre -like cells, some spindle- 

 shaped, some multipolar, the former lying in the so - called sub- 

 cuticular sheath, as we shall afterwards have occasion to notice. 

 The multipolar cells, which have been hitherto noticed only by 

 Schiefferdecker, possess a membraneless, finely granular protoplasm, 

 enclosing a very distinct nucleus, and running out into a varying 

 number of long, thin, sometimes even reticulated processes of a 

 sunilarly finely granular nature. They are found scattered through 

 the whole parenchyma, especially in large Tcenice, and sometimes 

 recall ganglion cells. 



The Calcareous Bodies. — We have already noticed these as distributed 

 through the body-parenchyma, and belonging specially to the cortical 

 layer. These concretipjis,jary j.n gjfe .iipi^g^ 0-019 mm., and have a 



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