PREFACE TO THE FIRST EDITION 



AVhat appeared altogether impossible twentj'-five jTars ago has in several 

 cases been attained by improvements in technique. Who would have believed 

 at that time that ultramicroscopes would now be manufactured in quantity, 

 built without any optical lenses, and capable of revealing a world of structures 

 quite beyond their ken? Who would have thought that a whole series of dif- 

 ferent atoms could be tagged and their distribution to the several tissues, when 

 introduced into the body, accurately measured? Who would have anticipated 

 the significant and unexpected new developments which have been made in 

 polarization optical methods? Had we been told twenty-five years ago that the 

 cell itself can be broken up into parts several of which can be collected in quantity 

 and chemically analyzed, we would have been incredulous. All this and more 

 has been achieved as a result of team work between the biological and physical 

 sciences. And we may believe that more surprises are in store. 



Yet some of us individually are still extraordinarily conservative in the 

 methods we use. The possibilities of improving old techniques, of replacing 

 some of them by new ones and of relying more upon microchemical and physical 

 procedures are not explored as they should be. The purpose of this book is to 

 extend the horizon bj^ exposing in an introductory way a few of the many oppor- 

 tunities awaiting workers in biology and medicine interested in the minute struc- 

 ture of living things. Success will depend upon ability to anticipate and meet 

 the needs of those likely to consult it. Definite information about specific 

 matters is likely to be more in demand than general statements. The latter are 

 limited to a few pages and deal with "choice of methods" and ''organization of 

 laboratory." 



Some may turn to the names of the structures in which they happen to be 

 most interested at the moment — Nissl Bodies, Nerve Fibers, Capillaries and so 

 forth — on the off chance of finding some useful hints as to methods better adapted 

 for their microscopic study, the most likely experimental errors and so on. Be- 

 cause the range of cells, parts of cells, tissues, organs and systems is obviously 

 so immense, mention is only possible of a small proportion of them so that much 

 depends on the selection made. 



Others may seek information under the headings of elements such as Iron, 

 Potassium and Calcium, of enzymes like Pepsin and Phosphatase and of many 

 other components of living material. It is diflScult to draw the line but most of 

 those that can be localized microscopically are mentioned, likewise techniques 

 for the determination of permeability, viscosity, pH and other properties of 

 tissues. 



It often happens, however, that data are required about a particular technique, 

 which the workers are using or expect to use, and which is known to them by 

 the names of those who discovered it, as for example the methods of Giemsa and 



