rUKFACE K) IHK FOURTH EDITION 



TnK rapid growth of intorost in the ohomical problems of iiiodical 

 and Ijiological science is shown by the groat incrcas(> in the amount of 

 mat(M'ial which must be inchided in (>aclisncceedinKe(Ution. Ahhoush 

 this hit(>st edition has hvcu subj(>cted to extensive revision and many 

 miiioi- alterations, yet tlu^ fieneral i)lan has not been changed. The 

 rapidly growing iiifoiination concerning the nutritional factoi-s that 

 are essential to growth and rej)aii-, and without which serious "Defi- 

 ciency Diseases" may arise, has necessitated the introduction of a new" 

 chapter to cover this subject, the importance of which has been ac- 

 centuated by the war and its sequels. The growing bulk of material 

 on the Reactions of Immunity reciuired a rearrangement of this 

 material, so that a separate chajiter on Anaphylaxis and Allergy has 

 l)een provided, foi- j)ur):)oses of convenience. Numerous sections 

 have been entirely rewritten, and few pages have not required re- 

 vision or addition. 



In order to prevent the increasing material that must be included 

 from resulting in too cumbersome a volume, much more of the matter 

 is printed in smaller type. It is hoped that this arrangement will 

 achieve its aim without serious reduction in facility of use. The author 

 recognizes fully that it w^ould be easily possible to report the existing 

 state of knowledge on the topics covered in "Chemical Pathology" 

 in a much ])riefer space, if only completely established evidence weie 

 included. "With the object of serving as a guide to investigators, and 

 with the hope of stimulating further investigations, much more than 

 this minimal amount of existing evidence is included. It is also recog- 

 nized that the brief discussion of the elementary principles of physical 

 chemistry and the fundamentals of the physics and chemistry of 

 living cells, which constitutes the introductory chapter, maj^ be out of 

 place in a work on Pathology, and the elimination of this chapter has 

 been seriously considered. Repeated assurances of the usefulness of 

 such a presentation, however, have resulted in its retention, at least 

 for the present. 



As with all previous editions, mj' indebtedness must be acknowl- 

 edged to numerous colleagues who have kindly read over the sections 

 of this book which most closely concern their own fields, and especially 

 to the members of my Department and of the Sprague Institute who 

 have made manj^ useful suggestions. The chapter on Diabetes is, as 

 before, contributed by Dr. R. T. AVoodyatt, Director of the Laboratory 

 of Clinical Research of the Otho S. A. Sprague ^lemorial Institute. 



H. G. W. 

 Chicago, III.. 

 July, 1920. 



