CONFIRMATION OF BONNET'S EXPERIMENTS. 65 



there is not one word of truth in the statements, and he 

 Liughs at Professor Owen for repeating them. I have exam- 

 ined the point, as regards the Nais, since reading his denial, 

 and am at a loss to understand how that denial could have 

 been made in terms so sweeping. In the Nais proboscidea- 

 the spontaneous separation is preceded by the formation of a 

 head, with the unmistakable proboscis; as anyone may observe 

 who will collect a few sj)ecimens from a neighbouring pond. 

 The JVa'is proboscidea is a convincing instance, because 

 the long proboscis may easily be seen projecting from the 

 segment where the separation will take place ; and its 

 presence removes all possible doubt as to the formation of h 

 new head. Disposed as I am to allow due weight to the 

 opinions of Dr Williams, I am surprised to find him saying : 

 " The tail-fragment never, as can be proved by easy observa- 

 tion, produces a single new ring or segment of the body. 

 If this be true, how completely improbable must be the 

 statement, that the headless piece is capable of constructing 

 a new head !" No one can read Bonnet's OAvn account of 

 his observations and experiments, recorded with great 

 minuteness and precision, Avithout feeling considerable 

 surprise at such a remark. If Dr Williams were correct, 

 his contradiction would for ever throw a doubt on the 

 observations of any naturalist ; because if Bonnet is not 

 to be trusted, on a point so easy of verification, when his 

 statements are so precise, and his observations so numerous 

 and minute, no one can be trusted. Fortunately, however. 

 Bonnet is rigorously correct. I have verified his observa- 

 tions under the impulse of Dr Williams's denial ; and at the 



