307 



some of the latter in soup to a criminal condemned to be exe- 

 cuted, and on dissection a Taenia very like T. solium was found, 

 with but three joints, and bearing a head of Echinococcus. This 

 T. ec/iinococcvs, as he calls it, had so long escaped observation 

 only from its diminutive size, it being only three lines in length. 

 The last proglottis of the three was perfect, and contained the 

 sexual organs. This is a late discovery, and must not be con- 

 founded with T. echinococcus of Siebold, who made the E. homi- 

 nis and E. veterinorum the same species. 



In our study of these important and interesting parasites we 

 notice three stages of development. First we see the proglottis 

 leaving the intestine, and apparently seeking in the outer world 

 of light and pure air some element, of which we are ignorant, for 

 the development of the embryo. It possesses fibres capable of 

 conti'acting after it has left the body, and finally discharges its 

 eggs from the ovi-sac. These lead a nomadic life till by chance 

 they once more gain admittance to their old haunts, where, in- 

 stead of remaining contented, they burrow at once into the tis- 

 sues, and then, after the formation of a head, leave them again, if 

 possible, to resume their former quarters in the intestine, where 

 the last stage of development is completed. 



We can but notice that the Taenia feeds upon matter which 

 has not been oxygenized or converted into tissue ; whereas in its 

 other state it exists upon the substance of animal life itself. Ivo- 

 kitansky noticed in the bladder of a Cysticercus, found in the 

 brain, shreds of nerve fibre ; and they must obtain from the hu- 

 man tissues they prey upon the great amount of calcareous mat- 

 ter found in their concentric corpuscles. What the object of 

 these is no man knows ; but the advancement in this branch of 

 observation within the last few years leads us to hope that 

 light may be thrown upon many points in their history, now 

 obscure. 



Dr. Gould read a communication from Mr. William 

 Stimpson, upon a new form of parasitic gasteropodous 

 moUusca, which he calls Cochliolepis parasiticus, as fol- 

 lows : — 



In the spring of 1852, while investigating the marine fauna of 



