VIU rKE-rA»^ii 



This is in no sense a text-book. There is, I hope, nothing dog- 

 matic in it. Its purpose is as much to show the gaps in knowledge 

 as to knit together what is surely known. The possibilities for re- 

 search in microtechnique seem endless, and every effort has been 

 made to point out as many of them as possible. 



The book contains a good deal of new material of three sorts. 

 First, there are new contributions to the theory of fixation and dye- 

 ing. Secondly, there are many factual observations that have not 

 been published previously. Thirdly, the Appendix contains full 

 descriptions of new experiments illustrating the principles under- 

 lying the processes of fixation and dyeing. Most of these can be 

 carried out in practical classes. 



There is in the whole book no practical instruction on how to 

 make a microscopical preparation. For this the reader should turn 

 to one of the excellent guides to the subject, such as Langeron's 

 Precis de microscopie^'^^^ or Pantin's Notes on microscopical technique 

 for zoologists. ^^^ 



Apart from my own little book on Cytological technique, "^^ I know 

 of only three that cover more or less the same field as the present 

 work. These are Fischer's Fixierung, Fdrbung und Ban des 

 Protoplasmas (1899),^^^ Mann's Physiological Histology (1902),^"^ 

 and Zeiger's Physikochemische Grundlageft der histologischen 

 Methodik (1938).^^^ There cannot be many equally important 

 fields of science to which so few books have been devoted — and 

 those few of such merit as these three. 



In the historical parts of the book I have adopted the usual con- 

 vention of giving as the date of a discovery the year in which it was 

 first made known in print. 



Acknowledgements. It was Mr Frank Sherlock, Head Technician 

 of the Department of Zoology, Oxford, w ho first gave me instruc- 

 tion in microtechnique, and I have always owed a debt of gratitude 

 to him. Dr H. M. Carleton was generous with good advice through- 

 out our association of thirty-five years. Prof. A. C. Hardy, F.R.S., 

 has encouraged cytological studies in his Department and I am 

 thankful for all that he has done to help me. Dr M. Wolman 

 generously sent me the proof of his article on fixation^^^ before it 

 was published. One learns best, perhaps, by continual association 

 with lively young minds, and it has been my good fortune for many 

 years to have a splendid succession of research-pupils from many 

 lands, to whom I owe much. I have alwa3^s been lucky in my assist- 

 ants and must particularly mention Mrs B. M. Jordan-Luke, 



