THK NEPHRIDIA OP LEECHES. 547 



C'est la uae vei'ite recouuue a tel poiut par tout le monde, 

 qu'il semble presque ridicule de la mentionuer. 



" Et cependant, lorsqu'il s'agit de Tapplication; cette verite 

 est trop souvent meconnue, 



''La matiere que nous allons traiter apres tant d'autres 

 savants en donne une preuve palpable. L'anatomie des orgaues 

 segmentaires des Hirudinees d'eau douce a ete le sujet de bien 

 de recherches. Neanmoins la structure exacte de ces mer- 

 veilleux organes n'a pas ete mise en lumiere par nos savants 

 devanciers. 



" La seule raison en est que les raoyens dont ils se sont 

 servis n^etaient point en proportion avec le but qu'ils se 

 proposaient d^atteindre." 



It is very sad and serious that so many pages of a journal 

 like that of the Societe Scientifique de Bruxelles should 

 be taken up by anatomical results which can easily be 

 shown to be erroneous ; but there is a humorous side to 

 the fact that M. Bolsius should blame his predecessors for not 

 using methods which were at the time when they wrote not 

 invented, or in their infancy, while his own errors are due to 

 neglect of the simple methods used by those whom he blames. 



Direct observation of hundreds of fresh nephridia and of 

 teased macerated preparations, aided by a comparatively rude 

 series of sections, enabled me to give twelve years ago an 

 account of the nephridium of the medicinal leech, erroneous in 

 many particulars as I afterwards discovered, but which I now 

 maintain was much nearer the truth in its general plan than 

 M. Bolsius' recent account. 



M. Bolsius has had enormous advantages in the methods at 

 his disposal,^ with this result, — led away by the fascinating 

 methods of serial section-cutting, he has almost entirely 

 neglected simple dissections. Dissection appears, indeed, to 



I I note that the staining fluid stated by M. Bolsius to give the best 

 results is oue of which the formula has not yet, he says, been published, but 

 one which is very much used iu the laboratory at Louvain. Tliis surely 

 savours somewhat of quackery. But M. Bolsius is probably not the person 

 to blame in the matter. 



