344 Prof. P. J. Van Beneden on the Intestinal Worms. 



The Louvain Professor, Van Beneden, responded to this prize- 

 question by an extensive work, which saw the light towards the 

 end of the past year. It cannot be a matter devoid of interest 

 if we give succinctly an outline of the principal contents of this 

 prize-memoir. Intestinal worms, by their presence in man, are 

 often the cause of various disturbances in the bodily functions, 

 whilst the peculiarities they offer in their organization, propa- 

 gation, and vital pha^nomena are of much importance for general 

 physiology. 



In his introduction the author considers the class of intestinal 

 worms, and their orders or groups, as they were adopted by 

 Cuvier in his ' Regne Animal.^ The class must first be divested 

 of foreign intermixture. Such a heterogeneous clement, espe- 

 cially, is formed by the Lernece {gill-icoi-ms, as they are often 

 named), pai'asites of fishes, which attach themselves not only to 

 the gills, but to other parts also, where the skin is thin. It 

 had become probable, thirty years ago, when Cuvier published 

 the second edition of his ' Zoology,' that these animals form the 

 transition to certain Crustaceans ; but that they really do belong 

 to the Crustaceans was first established, not long after, by the 

 investigations of V. Nordmann, and is now generally recog- 

 nized. Another foreign adjunct is formed by the genus Penia- 

 stoma, which also quits the egg in the form of an articulate animal 

 with articulate feet, and, by retrogression of organization, as- 

 sumes as it grows a similarity in form to a worm ; it was placed 

 alternately amongst the Trematodes and amongst the Nematoids, 

 but found its true place in neither of these two groups. It was 

 not until the early state of the Pentastomcs had been made 

 known that the true afiinity of this genus became apparent. 



After the elimination of these foreign constituents, the class 

 of intestinal worms, as Cuvier accepted it, still contains four 

 groups, the Nematoids, the Echinorhynchs [Acanthocephala) , the 

 Trematodes, and the Cestoids. That we do not subjoin a fifth 

 group, that of the Cystica, or vesicular worms, is a result of the 

 discoveries of the last eight years, which have shown that it rests 

 only upon youthful, undeveloped species of Cestoids. 



The limited time appointed by the Academy for answering 

 their prize-question did not allow the author to busy himself 

 with a complete and extended investigation of all the divisions 

 of the intestinal worms. He confined himself especially to the 

 Cestoids and Trematodes, and desires that what he has advanced 

 respecting the Nematoids and thorn-headed worms should be 

 regarded as a sample merely, and as such has subjoined it in a 

 supplement to his work. 



The first part of the treatise is devoted to the description of 



