TRANSMIGRATIONS AND METAMORPHOSES. 187 



life ; and it is not a matter of doubt to us that parasites 

 often play their allotted part in the economy; their 

 absence as well as their presence may be the cause of 

 inconvenience. We should not even be astonished if the 

 administration of certain worms internally should be 

 prescribed as a remedy. Have we not known the time 

 when all maladies were supposed to yield to the action of 

 leeches, and do we not see the good effects of their appli- 

 cation ? There are many kinds of parasites, and their 

 therapeutic effect may, perhaps, in future, form an 

 interesting subject of'study. 



To speak at the present time of a verminous tempera- 

 ment would be scientific heresy, an anachronism ; this 

 shows the progress that we have made of late years. 

 Valenciennes was permitted to employ this language at 

 the Academy of Sciences in Paris not twenty years ago, 

 and Lamarck wrote thus in his standard work on in- 

 vertebrate animals, in the beginning of this century: 

 "It is very certain that there exist in a great many 

 animals, and even in man, intestinal worms ; some of 

 which are formed there, others are born and all live 

 there, multiplying more or less, without any of these 

 worms showing themselves externally, or being able to 

 live elsewhere. 



" During so many centuries that observations have 

 been made, well-ascertained species of intestinal worms 

 have been found nowhere else than in the bodies of ani- 

 mals. We are now authorized to believe that there are 

 innate worms, or such as are produced by spontaneous 

 generation, and that these are modified from time to 

 time ; this is at present the opinion of the most en- 

 lightened observers." 



