XXV11 



experimental physiology, to which Sachs had already so largely con- 

 tributed. Then there are his classical papers on the structure of and 

 the arrangement of cells in growing-points ; and finally the papers in 

 which he elaborated his "imbibition-theory" of the transpiration - 

 current. Though it now seems probable that this theory is insuffi- 

 cient to explain the facts — the problem, however, still remaining 

 unsolved in spite of many subsequent attempts at solution — yet these 

 papers contain a great mass of important observations, the result of 

 enormous labour and experimental skill, which must be taken into 

 account by all who attempt investigation in this direction. This 

 volume also contains the noteworthy papers on " Stoff und Form 

 der Pnanzenorgane," an attempt at a material explanation of the 

 differences distinguishing the chief members of the plant-body, as 

 also the various metamorphosed forms of one and the same member. 

 This attempted explanation, though it cannot be said to have met 

 with general acceptance, has still its adherents, and is to some 

 extent borne out by his subsequent observations, published in the 

 third volume of the ' Arbeiten," on the suppression of the develop- 

 ment of flowers in plants grown in light which has passed through 

 a solution of quinine, and has consequently lost the ultra-violet 

 rays. 



The third volume of the 'Arbeiten' (1884-88) contains relatively 

 little of Sachs' own work. The only paper of importance, in addition 

 to the one just mentioned, is that entitled " EinBeitrag zur Kenntniss 

 der Ernahrungsthatigkcit der Blatter," which is an exhaustive study 

 of the assimilatory activity of the leaf, as also of the distribution of 

 the products of this activity from the leaf to the rest of the plant. 



With this third volume Sachs' work as an investigator may be said 

 to have closed, though he subsequently published from time to* time 

 in' Flora,' a series of " Physiologische N"otizen " which, though slight, 

 never failed to be suggestive aud interesting, as his writings always 

 were.* 



Amongst the more important of his achievements whilst Professor 

 at Wiirzburg must be reckoned his ' Geschichte der Botanik ' and 

 his ' Vbrlesttngen ueber Pflanzenphysiologie.' In these works his 

 great literary ability had scope to display itself. The style is lucid, 

 with many brilliant passages - and the matter, widely different as it 

 is in the two books, is handled with complete mastery in both. The 

 1 Geschichte,'| which appeared in 1875, though by no means a bulky 

 volume, presents a vivid picture, heightened here and there with 

 touches of caustic criticism, of the gradual development of the 

 science from the middle of the sixteenth century up to the year 1860. 

 It is not only brilliant, but also learned, and its preparation must 



* An edition of Sachs' collected papers was published in 1892-93. 



t An English translation was published by the Oxford University Press in 1890. 



