2G DISCOVERY OF PHOTOSYNTHESIS CHAP. 2 



equation (2.7) is complete; its further elaboration could result only from 

 detailed quantitative investigations, of the kind inaugurated by Bous- 

 singault in 1864. 



The discovery of photosynthesis has engendered bitter rivalries, and 

 historians have kept the flame of hate alive long after the principal actors 

 in the drama have been silenced by death. The biographers of Priestlej' 

 have felt that the discovery has been unfairly snatched away from this 

 great experimentalist; the biographer of Ingen-Housz, Wiesner (1905), 

 had no doubts that all honors belong to his hero, who "always kept his 

 fights noble and magnanimous, even after Priestley had attempted base- 

 lesslj^ to defame his reputation and Senebier had undertaken to put him- 

 self into the possession of his discoveries by dishonest means. The most 

 he has ever allowed himself has been gentle, nicely expressed irony." 

 The friends and compatriots of Senebier, including de Saussure, and later 

 N. Pringsheim (the latter mainly for reasons of his disagreement with 

 everything Sachs stood for), were inclined to attribute to him, if not the 

 whole, at least a large part of the discovery. 



We are now sufficiently remote from these controversies to be only 

 mildly interested in the questions of priority and personal ambitions, 

 and to recognize the discover}^ of photosynthesis as the inevitable conse- 

 quence of the two great achievements of science in the period between 

 1770 and 1840 — the discovery of chemical elements, and the creation of 

 the concept of energy. The work of the five men whose names are associ- 

 ated with the foundations of photosynthesis, Priestley, Ingen-Housz, 

 Senebier, de Saussure and Robert Mayer, has evolved from this back- 

 ground, which two of them, Priestley and Mayer, themselves helped 

 to create. 



After 1860, the development of plant physiology in general, and of 

 photosynthesis in particular, took a rapid spurt, under the leadership of 

 such men as Sachs, Pfeffer and Timiriazev. From this time on, the 

 literature on photos,ynthesis has grown precipitously, initil now a complete 

 review of all papers on this subject, scattered through botanical, agri- 

 cultural, chemical and physical journals, appears almost impossible.* 

 This broad development of the subject of photosynthesis after 1860, which 

 has branched into manj'- different fields, including in addition to plant 

 physiology also organic chemistrj-, physical chemistry and physics (not 

 to speak of ecology and other branches of botany), makes it advisable to 

 close here the historical introduction, and to deal henceforth with the 

 different aspects of photosynthesis in a logical rather than chronological 

 order. 



* A list of about 900 investigations published before 1925 can be found in W. Stiles' 

 monograph, Photosj/nlhesis. The subject was treated in an even more comprehensive 

 manner one year later, in the well-known monograph, of the same title, by H. A. Spoehr 

 (1926j, which, however, does not contain a list of bibliographical references. 



