26 



snail, {Helix pomatia,') and in a beetle, {Tenebrio molitor,) and 

 in the cyst were found six little spines thrown off by the embryo. 

 Thus, we have reason to believe that that hatching embryo, 

 with its six spines, penetrates into an insect or a mollusk, forms 

 there a pupa, loses its spines, and waits in this state till the snail 

 or the insect is swallowed by a vertebrate ; for in vertebrata only 

 we find pei'fect tapeworms. In the case of Taenia punctata., we 

 may suppose that the embryo enters an insect, forms there a 

 pupa, which afterwards is eaten with the insect by the wood- 

 pecker, and then is developed into a tapeworm. Thus, the 

 intimate I'elations existing between the woodpecker, its tape- 

 worm, and the insects in which the latter lives as a pupa, and 

 upon which the woodpecker feeds, must be intimately concerned 

 in the preservation of the species of this worm ; and if we con- 

 sider how infinitely small is the chance of a single egg's per- 

 fecting its development in that bird, we see why one tapeworm 

 should furnish millions of eggs in a year. 



The Psorosperraia, discovered first by Johannes Miiller, which 

 may be another larval state of a worm, Dr. Weinland had found 

 by thousands attached to the hind part of the eye bulb of the 

 American Haddock, {Gadus aeglefinus.) 



To a question proposed by Dr. Gould, " Whence come the 

 parasitic worms of the Foetus in Utero ? " Dr. Weinland an- 

 swered, that only two or three such instances are known ; and 

 from the f;ict that he once witnessed an Ascaris penetrating a 

 membrane in such a manner, that, after it had traversed it, there 

 was not to be seen any perforation in the membrane, (the worm 

 having separated the fibres of the tissue without tearing it,) he 

 thought that he could explain the presence of the worms, found 

 in the embryo, by a passage from tlie abdomen of the mother and 

 through the walls of the womb, and thence into the body of the 

 embryo ; a movement which, according to this observation in 

 Ascaris, could be effected without wounding the tissues. 



Mi\ Charles J. Sprague exhibited a beautiful specimen of a 

 parasitic fungus growing upon the body of a beetle, a species of 

 Sphoeria.. He said he supposed that the insect more or less com- 

 pletely buries itself in the eartli, and then the plant attaches 

 itself to its surface, and sooner or later destroys it. Mr. Sprague 



