571 



far than that of which the laminae of the cyst are formed. 

 This granular matter is prolonged beyond the mass of 

 Echinococci into a short pedicle, common to the whole, and 

 by which the granulation is attached to the interior of the 

 hydatid cyst, as represented in No. 101. In specimens 

 preserved in spirits, Echinococci of all imaginable forms and 

 appearances are to be met with, differences owing to de- 

 composition or to mechanical injury ; and in many cases 

 no traces of them can be found except the booklets or 

 spines, -which, like the fossil remains of animals in 

 geology, remain as certain indications of their source, and 

 not unfrequently afford the only proof we can obtain of 

 the true nature of the hydatid." 1 



The Echinorhynchi, or Acantho cephali, constitute a 

 group of entozoa, with respect to whose development and 

 life-history we are indebted to Prof. Leuckart of Giessen. 

 Most observers, and in particular Von Beneden and G. 

 Wagner, have been disposed to assign to the Echinorhynci 

 a simple metamorphosis, hardly perhaps more remarkable 

 than that which has been shown to take place in some 

 other of the Nematode worms. The latter observer goes 

 so far even as to believe that the organization of the per- 

 fect animal may be discerned in the embryo. Leuckart 

 instituted, in 1861, a series of experiments with the ova 

 of Echinorhynchm Proteus, which is found parasitic upon 

 the Gammarus Pulex. The ova " of E. Proteus resemble 

 in form and structure those of the allied species. They 

 are of a fusiform shape, surrounded with two mem- 

 branes, an external, of a more albuminous nature, and an 

 internal, chitinous one. When the eggs have reached the 

 intestine, the outer of these membranes is lost, being in 

 fact digested; whilst the inner envelope remains until 

 ruptured by the embryo." 2 



Anguillulce are very small eel-like worms, of which one 

 species, 3 Anguillula fluviatilis, is found in rain-water 

 amongst Confervas and Desmidiacece, in wet moss and 

 moist earth, and sometimes in the alimentary canal of the 



1) Microscopical Society's Transactions. 1st Seriee. 



(2) Prof. Leuckart "On Echinorhynchus." Journ. Micro. Soc. voL iii. p. 57. 1863. 



(3) For the fullest information of marine, land, and fresh-water species, con- 

 It Dr. Bastian's "Monograph on the Anguillulida." Lin. Soc. Trans. voL 



xxv. p. 75. The "Anguillula Aceti." Popular Science Review, January, 1863. 



