IV PREFACE 



of Plant and Animal Life," and includes the composition 

 of plant, and animal bodies, the chemistry of the plant 

 and of its food and growth, the chemistry of human 

 foods and animal nutrition, the digestibility and value of 

 foods and the laws governing their economic use. A few 

 topics of an industrial nature but closely related to plant 

 and animal life are also included. 



Before taking up the special parts relating to the chem- 

 istry of plant and animal bodies, the elements and simpler 

 compounds present in plants and animals, together with 

 the laws governing their combinations, are considered so 

 as to prepare the way for a more intelligent study of the 

 subject. Laboratory practice forms an important feature, 

 and questions are asked in connection with each experi- 

 ment. Many of the experiments and problems are given 

 to illustrate some special feature of the composition of 

 plant and animal bodies. The illustrations, with the 

 exception of a few as noted, are original. 



With mature earnest students, six months with a class- 

 room or laboratory exercise each day are required to 

 complete this work, although a longer time could ad- 

 vantageously be given to the subject. It has been the 

 aim throughout to present the topics in such a way that 

 they would be easily understood and to develop the rea- 

 soning powers of the student so that he would be able to 

 make the best use of his chemistry in every-day life af- 

 fairs. HARRY SNYDER. 



March i, 1903. 



