ON THE ANATOMY OF ECHINOCOCCUS VETERINORUM 20I 



puscles of the cestoid and cystic Entozoa usually contain an albumi- 

 nous substance, and sometimes a fatty matter, but that this is very 

 liable to become replaced by a calcareous substance. 



Homologically, I think they are identical with the peculiar, elon- 

 gated, strongly refracting, solid bodies, contained in the skin of both 

 the Dendroccele and Rhabdoccele Turbellaria, which in some marine 

 Planar ia-ldirv^, according to Prof Johannes Muller, are developed 

 into true thread cells, similar to those of the hydroid Polypes. The 

 thread cell of the latter is equally developed as a secondary deposit 

 within a vesicle (nucleus .') contained in the cells of the body ; the 

 only difference would be, that whereas in the Polype the succeeding 

 internal deposit takes place in the form of a spiral thread, in the 

 cestoid or cystic Entozoon it takes place as a succession of simple 

 layers, until the vesicle is full. 



Aware of the discoveries that have been lately made by Siebold, 

 Van Beneden and Guido Wagner, as to the extent to which the water 

 vascular system is developed in the Cestoid Entozoa ; and unac- 

 quainted with what had been observed by Dr. Lebert^ (vide infra), 

 I particularly endeavoured to detect, in the quite fresh Echinococci, 

 some evidence of its existence, and I was so far successful that I 

 could very readily observe in several specimens (examined on the 

 first day) a number of the peculiar flickering cilia so characteristic of 

 this system of vessels wherever it exists. In spite of all my en- 

 deavours, however, I could trace nothing of the vessels themselves, in 

 which, by analogy, one has every reason to believe the cilia are con- 

 tained. ^ In one Echinococcus I observed six of these long flicker- 

 ing cilia in the positions indicated by the short wavy lines in fig. i 

 (PI. XXVIII. [Plate 2i]). They were so distinct as to be perfectly 

 measurable, their length being about 3,Voth of an inch. They were 

 excessively delicate, but broader at the fixed than at the free end, 

 and they completely resembled the corresponding organs in the 

 Rotifera^ Naida, &c. 



Professor Owen has stated (article Entozoa, Todd's Cyclopaedia, 

 1839) that the Echinococci (from the Pig) which he examined, moved 

 "freely by means of superficial vibratile cilia," p. 118. There were 

 certainly no such cilia upon the Echinococci of the Zebra. 



1 Prof. Virchow, and the colleagues before whom he laid his observations upon the 

 occurrence of cilia in the pedicle of Echinococcus (vide infra), appear equally to have 

 overlooked Dr. Lebert's excellent paper, although it is contained in MiiUer's Archiv for 

 1843. 



"- In the Planaria torva I have similarly observed the cilia but not the vessels. 



3 See the essay by the author on " Lacinularia socialis," &c. &c. in the Microscopical 

 Journal, No. 1, 1852. (Supra, p. 126). 



