ZOOLOGY. 



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 perfect tape- 

 worms. In the case of Twnia punctata, we may suppose that the embryo 

 enters an insect, forms there a pupa, which afterwards is eaten with the 

 insect by the woodpecker, and then is developed into a tapeworm. Thus, 

 the intimate relations existing between the woodpecker, its tapeworm, and 

 the insects in which the latter lives as a pupa, and upon which the wood- 

 pecker feeds, must be intimately concerned in the preservation of the species 

 of this worm; and if we consider how infinitely small is the chance of a 

 single egg's perfecting its development in that bird, we see why one tape- 

 worm should furnish millions of eggs in a year. 



The Psorospermia, discovered first by Johannes M tiller, which may be 

 another larval state of a worm, Dr. "\Veinland has 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. Wcinland answered, that only two or three 

 such instances are known; and from the fact 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 the abdomen of the mother and through the walls of the 

 womb, and thence into the body of the embryo; a movement which, ac- 

 cording to this observation of Ascaris, could be effected without wounding 

 the tissues. 



ON THE TAPEWORM. 



One of the most valuable contributions recently made in pathology and 

 zoology is an essay by Dr. D. F. Moreland, of Boston, entitled "The Tape- 

 worms of Man: their nature, organization, embryonic development, the 

 pathological symptoms they produce, and the remedies which have proved 

 successful in modern practice." 



The following extracts from its pages, made by the editors of Sittiman's 

 Journal, will be found to contain facts of a most curious and interesting 

 character : 



Every butcher is acquainted with the disease in the muscles of the 

 domesticated hog, denominated " measles," and calls the flesh of such a hog 

 " measly pork." It has long been known that those pea-like whitish globules 

 (measles) contain a curious animal, namely, the perfect head and neck of a 

 tapeworm, ending, however, not in the long jointed body of the regular 

 tapeworm, but in a water-bladder. No traces of reproductive organs are to 

 be seen. Such measles are found not only in the hog, but also in other ani- 

 mals, where they are better known under the name of Hydatids. For exam- 

 ple, they are very often met with in the liver of rats and mice; in the me- 

 sentery of the hare; and even, though more rarely, in the muscles of man; 

 and those of the latter have turned out to be of the same species ( Cysticerots 

 Cellulosce., Rudolphi) as those found in the hog. All the different species of 

 this sort of hydatids arc known in science under the generic name of 

 Cysticercus. 



Again, other hydatids, varying from the size of a pea to a diameter of 

 .several inches, are occasionally found in the lungs, the liver, and other 



