Vlll PREFACE. 



announcement of which appeared some months since, and 

 towards the completion of which considerable materials have 

 already been collected. 



To Mr. Hett my thanks are especially due for having, at 

 considerable trouble and inconvenience, furnished me with 

 very many of the injections required to illustrate Part XV. 

 of the " Microscopic Anatomy ; " these, together with nu- 

 merous other injected preparations of that gentleman which 

 I have seen, have been of first-rate quality ; and the mi- 

 croscopic anatomist has reason to hail the advent of such 

 a man to the cause of general anatomy with the highest 

 satisfaction. 



To Mr. Andrew Ross, on this, as on a former occasion, I 

 have to express my obligations, Mr. R. having at all times 

 furnished me with any information I might require, as well 

 as provided me with any necessary apparatus. 



Thus much for friends. If in the inditing of this work I 

 have made a single enemy I am sorry for it, and still more 

 so if I have given any real occasion for offence. If in differing 

 from other observers as to certain facts and conclusions I 

 have expressed myself in such a manner as to wound their 

 feelings, as in one or two instances I fear I may have done, 

 I much regret it : the differences amongst men whose com- 

 mon aim is the knowledge of truth as manifested in the 

 works of creation should never be deep or lasting ; for this 

 community of purpose should ever be a firm bond of union 

 between such men, seekers after truth, and should displace 

 from their minds the lesser and grosser feelings of rivalry 

 and ill-will. 



Netting Hill, 

 July 27th, 1849. 



