X PREFACE. 



very important chapter on the ' Contractile Tissues/ and in 

 such a manner as will, I feel sure, attract the good opinion 

 of physiologists. Mr Priestley had, without any intention 

 of writing on the subject, made himself so thoroughly 

 master of all that had been written on the subject of the 

 physiology of muscle, that in the best interests of my 

 readers I asked him to assist me in dealing with this 

 subject. Although any credit which it may merit is due to 

 Mr Priestley for the greater part of this chapter, I must in 

 justice to myself say that every section and almost every 

 sentence in it have been the subjects of discussion be- 

 tween us. 



I have been helped by Mr William Dodgson in the 

 reduction of the valuable tables of blood-spectra of Pro- 

 fessor Preyer to a scale of wave-lengths, and in the 

 actual drawing of the scale attached to the spectra of 

 haemoglobin and its derivatives. I may here incidentally 

 remark that in the description of spectra of any import- 

 ance I have referred all measurements to wave-lengths, 

 taking care to check the reduced observations of others by 

 measurements made with the help of one of Herr Zeiss's 

 beautiful spectroscopes furnished with a scale of wave- 

 lengths. 



Lastly, I have to express my deep obligations to Dr 

 Alfred Young, to Mr Marcus Hartog, M.A., and to my 

 pupils Messrs Larmuth, Reynolds, and William Thorburn 

 for much useful help. Upon the first of these gentlemen 

 devolved the greater part of the labour of preparing a full 

 and accurate index. 



ARTHUR GAMGEE. 



Manchester, 



July, 1880. 



