WORMS. 203 



a delightful and interesting source of study they 

 afford us ; and by such study are they not instru- 

 mental in enlightening our minds, in developing our 

 pensive faculties, upon which the entire happiness 

 of our race depends ? 



Greater marvels still await us in the numerous 

 tribes of Helminthes, or intestinal worms. In these 

 curious beings the organs of sense appear to be 

 limited to that of feeling (or touch) ; in some diges- 

 tive organs are altogether wanting, and their nutri- 

 ment penetrates their tissues as it would those of a 

 fungus or a conferva. No breathing apparatus is 

 required here how could it be otherwise with 

 creatures who live constantly shut up in the tissues 

 of other animals, often in cells or cavities which do 

 not communicate with the external air? These 

 curious animals are reproduced either by a sort of 

 budding, by spontaneous division, or by eggs. 

 When the two sexes exist, they are either found 

 united on the same individual, or there exist distinct 

 males and females. In these cases the young animal 

 is developed from an egg; but between the egg 

 period and that of the perfect animal, we observe, 

 as in insects, mollusca, Crustacea, and we may say, 

 in fact, all other animals, a series of metamorphoses 

 or transformations which, in the worms of which we 

 speak, are exceedingly remarkable. Thus the em- 

 bryo developed from the egg does not always grow 



