VI PREFACE. 



taken to mean that during synthesis the products of activity are altered in their 

 molecular peculiarities in specific relationship to the stereochemic modifications 

 of the forms of protoplasm which produce them. In other words, one may lay 

 down the dictum that each and every form of protoplasm existent in any organism is 

 stereochemically peculiarly modified in specific relationship to that organism, and that, 

 as a corollary, the products of synthesis will be modified in conformity with the 

 molecular peculiarities of the protoplasm giving rise to them. It follows, therefore, 

 that if the plastids of any given plant be of different stereochemic structure from 

 those of others, the starch produced will show corresponding stereochemic variations, 

 and hence he absolutely diagnostic in relation to the plant. Abundant evidence will 

 be found in the pages which follow in justification of this statement. Moreover, 

 if such differences are diagnostic, it is evident that they constitute a strictly 

 scientific basis for the classification of plants. 



The author takes advantage of this opportunity to record his heartfelt obli- 

 gation to the Carnegie Institution of Washington for the grants which made this 

 investigation possible; and also to President R. S. Woodward and Dr. S. Weir 

 Mitchell for invaluable assistance assistance easy of mention, but difficult of 

 adequate expression. 



Edward Tyson Reichert. 

 From the S. Weir Mitchell 



Laboratory of Physiology, 



University of Pennsylvania, April, 1912. 



