PREFACE. VI 1 



and should this publication succeed in rendering any service to 

 scientific literature in England, it will be a peculiar gratification 

 to me, to feel that I have repaid in some measure the obligations 

 which I owe to that country, in which I have found so many 

 sincere friends, and have gathered so much valuable instruction. 



In conclusion, I cannot refrain from recording my grateful 

 obligations to Messrs. J. W. Parker and Son, who have not 

 hesitated to incur the additional expense of engraving anew all 

 the woodcuts from my original drawings, and have, in every other 

 respect, advanced the interests of my work. 



A. KOLLIKER. 



AVUrzburg, April, i860. 



