164 SCIENCE PROGRESS. 



priority in them may justly be disputed if this expression 

 be taken to denote the pretension to have first seen or 

 spoken of a thing, . . . the lucid, confident recognition of it 

 is however due to Mohl's observation." But in Sachs' case 

 the remark applies not merely to the observation of facts, 

 to which Mohl confined himself, but to the brinoqno- into 

 prominence the importance of such facts in their relation to 

 the common stock of our knowledge, and to the risfht 

 ordering of observations in the general building- of know- 

 ledge ; work on which he laid great stress. He writes : 

 "As I read your book I feel anew how much more merit 

 there is in working out a comprehensive subject from reliable 

 sources, and from a higher standpoint, than in constantly 

 supplying fresh contributions, which, however meritorious 

 in themselves, are yet as the scattered stones of the hillside 

 compared to milestones pointing us on our way ! " 



Sachs is best known and most famous as the founder of 

 the modern physiology of plants, and his physiological 

 works may be next touched upon. " My earliest treatises," 

 he once wrote, "were composed at a time when the physio- 

 logy of plants was simply non-existent ; I myself was 

 entirely self-taught and consequently much of my work was 

 imperfect, especially the manner of exposition." Neverthe- 

 less these earlier works are of great importance. Next 

 to be named come his works upon chemical philosophy. 

 The investigations of Inoenhouss, Th. de Saussure, Liebio-, 

 Boussingault and others had supplied the foundation upon 

 which, in connection with the results of plant-anatomy, a 

 more exact knowledge of the phenomena of metabolism 

 was to be built up. It was Sachs who first pointed out 

 "that the starch in chlorophyll is not merely a secondary 

 deposit but must be regarded as the product of the assimi- 

 lating activity (produced by the action of light) of the 

 granular, chlorophyll substance : that it is formed in the 

 chlorophyll out of its original elements and is conducted to 

 the growing buds and to the tissues which store up the 

 reserve material" 1 : a brilliant addition to our knowledge, the 



1 Collected Essays, p. 335. 



