VI. INTRODUCTION. 



the better for descriptions which secure against failure. Such are 

 the descriptions found in this book. Indeed, the chief satisfaction 

 I derive from being allowed to write this foreword arises from the 

 opportunity it gives me of bearing witness to the fact that the 

 author has always a first-hand acquaintance with his subject matter. 

 In connexion with the newer, and less familiar, tests and methods 

 the directions are not copied from elsewhere, not even (when they 

 are due to others) from the descriptions of their originators. They 

 have been written at the laboratory bench, step by step with the 

 successful accomplishment of the process they describe. When 

 success has seemed doubtful, or too difficult of attainment, the 

 method has found no place in the book. Older methods have often 

 been modified in detail, as a result of long experience of their use in 

 practical classes. On the other hand not a few of the processes 

 described are original. It is indeed a pleasant duty to emphasise 

 the fact that the book is used as a medium for the publication of a 

 considerable amount of patient research work requiring abilities of 

 a special order. It is to be trusted that this work will receive the 

 same degree of recognition that it undoubtedly would if it were 

 published through the more ordinary channels of the scientific 

 periodicals. 



Some of the sections are intended for purposes wider than that 

 of class instruction alone. In the chapter on the preparation of the 

 amino-acids for instance, Mr. Cole has drawn on the collective 

 experience of many workers in my laboratory. The descriptions 

 are unique in their wealth of detail, and I feel confident that the 

 preparation of these compounds by the methods described can be 

 undertaken with every prospect of success by all workers. A 

 supply of pure amino-acids is so important for the prosecution of 

 many lines of research that the inclusion of the chapter will be 

 welcomed by many who have been disappointed at the results 

 of their previous attempts. Of my own knowledge I can testify 

 to the success that has attended the preparation of histidine and 

 tryptophane, for example, by junior laboratory attendants following 

 the descriptions here published. 



In my experience the teaching of practical biochemistry to 

 students of physiology presents a difficulty less felt in the practical 

 teaching of the other branches of the science. A successful histo- 



