vi PREFACE 



hitherto unpublished, I have selected a few of 

 those which appeared to be of most interest, and 

 in this I have of necessity been obliged to confine 

 myself to those which were most fully written 

 out. Where amplification was required I have 

 endeavoured, as far as possible, to do this in 

 words which, from my own personal knowledge, I 

 believe would have been used. 



The lectures on the Darwinian Theory, which 

 form a distinct course by themselves, will be 

 published as soon as possible in a separate volume, 

 together with other series of lectures, if there 

 appears to be a sufficient demand for them. 



I must express my thanks to the Committees 

 of the Manchester Microscopical Society, the 

 Birmingham Natural History Society, and the 

 British Association for permission to reproduce the 

 addresses printed in their Transactions. 



I am under great obligations to Professor G. B. 

 Howes for his kindness in reading the proofs, and 

 for supervising the technical points. My thanks 

 are also due to Professor Ray Lankester for valuable 

 suggestions, to my brother Mr. P. E. Marshall for 

 correcting the proofs, and to Dr. C. H. Hurst for 

 assistance on several points. 



C. F. MARSHALL. 



LONDON, April 1894. 



