xiv INTRODUCTION 



size and complexity, but also a greater variety of definite chemical 

 compounds than exist in any other known mixture, either mineral 

 or organic in type. One of the first problems in the study of 

 protoplasm is, therefore, to bring this great variety of complex 

 compounds into some orderly classification and to become -familiar 

 with their compositions and properties. Again, living matter is 

 continually undergoing a process of breaking down as a result of 

 its energetic activities and of simultaneously making good this 

 loss by the manufacture of new protoplasm out of simple food 

 materials. It also has the power of growth by the production of 

 surplus protoplasm which fills new cells, which in turn produce 

 new tissues and so increase the size and weight of individual 

 organs and of the organism as a whole. Hence, a second field of 

 study includes the chemical changes whereby new protoplasm 

 and new tissue-building material are elaborated. Finally, living 

 material not only repairs its own waste and produces new material 

 of like character to it, but it also produces new masses of living 

 matter, which when detached from the parent mass, eventually 

 begin a separate existence and growth. Furthermore, the plant 

 organism has acquired, by the process of evolution, the ability 

 not only to produce an embryo for a successive generation but also 

 to store up, in the tissues adjacent to it, reserve food material for 

 the use of the young seedling until it shall have developed the 

 ability to absorb and make use of its own external sources of food 

 material. So that, finally, every study of plant chemistry must 

 take into consideration the stored food material and the germina- 

 tive process whereby this becomes available to the new organism 

 of the next generation. Also, the chemistry of fertilization of the 

 ovum, so that a new embryo will be produced, and the other 

 stimuli which serve to induce the growth phenomena, must be 

 brought under observation and study. 



A further step in the development of biological science has 

 been to separate the study of living things into the two sciences of 

 botany and zoology. From the standpoint of the chemistry of 

 the processes involved this segregation is unfortunate. It has 

 resulted in the devotion of most of the study which has been given 

 to life processes and living things to animal chemistry, or " physi- 

 ological chemistry." As a consequence, biochemistry, which 

 deals with the living processes of both plants and animals, is yet 

 in its infancy; while phytochemistry is almost a new science, 



