302 LEIDY'S DESCRIPTIONS OF DISTOMA. 



five inches in length, of Tania canina, in the intestine of a small terrier dog, and Krause 

 mentions an instance of a two and a half year old horse, which contained over 519 

 Ascaris megalocephala, 191 Oxyuris curvula, 214 Strongylus armatus, var. major, 69 

 Tcenia perfoliata, several thousand Strongylus tetracanthus in the intestines, 287 

 Filaria papillosa in the thoracic and abdominal cavities, and 6 Cysticercus Jistularis 

 upon the peritoneal covering of the liver.* Numerous other instances might be 

 given to demonstrate the extent of entozoic vitality, but those I have mentioned will 

 suffice. 



All animals under certain circumstances become the residences of entozoa, and 

 these appear to be most frequently presented as we descend in the scale of organic 

 activity of animal life. Entozoa are most frequent among invertebrata, next among 

 fishes, then reptiles, and least so among birds and mammalia. My much respected 

 friend, Dr. Samuel Jackson, Professor in the University of Pennsylvania, entertains 

 the opinion, as animals descend in the series, and higher ones undergo a degradation 

 of structure, as in disease, they become more liable to entozoic life, and he has 

 mentioned to me the fact, that the well-fed and nutritioned inmates of our hospitals, 

 in post mortem examinations, seldom present the existence of intestinal worms, when 

 compared with the accounts of post mortem examinations of the hospitals of 

 continental Europe. In connection with this opinion arises the question whether 

 entozoa are the cause or effect of disease. From my observations I am inclined to 

 believe, with the distinguished helminthologist Dujardin, that they are usually the 

 effect of disease, as is expressed in the preface to his excellent work entitled " Hist 

 nat. des Hplminthes."t " D'apres cela, on peut se demander si les helminthes sont 

 veritablement nuisiWes aux animaux dans lesquels ils habitent? je suis pour la 

 negative, tant j'ai vu d'exemples d'animaux bien portants qui contenaient plus 

 d'helminthes que d'antres individus de chetive apparence : les helminthes se 

 developpent dans un'site qui leur convient, sans nuire plus que les lichens sur I'ecorce 

 d'un arbre vigoureux. lis ne peuvent devenir nuisible, generalement, que par suite 

 d' une multiplication excessive, laquelle semble alors etre une des consequences d'un 

 affaiblissement provenant d'une tout autre cause, d'une mauvaise alimentation, du 

 sejour dans un lieu froid et humide, etc.; sans cela, les helminthes naissent et 

 meurent dans le corps deleurs botes, et peuvent paraitre et disparaitre alternativement 

 sans inconvenients." 



After these general remarks upon Entozoa, I present to the Academy descriptions 

 of two species of Distoma, which I suppose to be new, with the partial history of one 

 of them. 



* Guilt u. Hertwig's Magazia flir die gesammte Thierheilkunde, 1839, S. 215. Wiegman's Archiv, 1840, S. 196. 

 t PariSj 1845, p. xiii. 



