Zoological Society. 



Having paid great attention to the process, however, I can 

 decidedly affirm — 



1 . That acetic acid dissolves out the contents of the corpuscles in 

 young and fresh Echinococci^ without the least evolution of gas from 

 them ; and that the same assertion holds good of the corresponding 

 corpuscles contained in the spirit specimens of Tcenia and Bothrio- 

 cephalus which I have examined. 



2. That caustic ammonia produces little cavities and sometimes a 

 concentric lamination in these bodies. 



And, 3rdly, that in a spirit specimen of an Echinococcus from the 

 Panther (which Dr. Hyde Salter kindly lent me), the corpuscles ap*- 

 peared vesicular without the action of any reagent. ' 



It may be said then, that the peculiar strongly refracting cor- 

 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 Dendrocoele and Rhabdocoele Turbellaria, which in some marine 

 Planaria-\2ir\2idy according to Prof. Johannes Miiller, 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 endea- 

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

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

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

 ing cilia ; they were so distinct as to be perfectly measurable, 

 their length being about g^yVo^^ ^^ *^ inch. They were excessively 

 delicate, but broader at the fixed than at the free end, and they com- 

 pletely resembled the corresponding organs in the Motif era%, 

 NaiadcBy &c. «« gikw 2-ym -i^^gair ^jBoiiob liif^.l') 



* Prof. Virchow, and the cdllfeagtie'^'b^fore whomhe laid tiis observafibns tipdh 

 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 Miil- 

 ler's Archiv for 1843. 



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



X See the essay by the author on "Lacinularia socialise &c. &c." in the Quarterly 

 Journal of Microscopical Science, No. 1, 1852. 



