WILHELM PFEFFER. 501 



Pfeffer was born, the son of an apothecary, in the village of Greben- 

 stein near Cassel, March 9, 1845. He studied at Gottingen where he 

 took his doctorate in 1865, in Marburg, where he afterward taught as 

 docent, in Berlin and Wiirzburg, in the latter University working 

 under Sachs. 



In 1873 he was appointed professor extraordinarius in Bonn, and 

 four years later went as full professor to Basel, where he remained only 

 a year, after which he went to Tubingen. He held the position in 

 Tubingen until his final removal in 1887 to Leipzig where he remained 

 until his death in 1920. 



In Leipzig he developed the great laboratory which for more than 

 thirty years was the Mecca for students of plant physiology from all 

 parts of the world. Throughout his long career in Leipzig he was 

 generally recognized as the first physiologist of his generation. 



While Pfeffer's name is primarily associated with strictly physiologi- 

 cal problems, as a young man he published several morphological 

 papers of considerable importance. Especially valuable was a paper 

 on the development of the gametophyte and embryo of Selaginella, a 

 paper that for a long time was the most important contribution to the 

 subject. 



It is, however, upon the very numerous and important contributions 

 to plant physiology that his fame rests. These cover an extensive 

 range of subjects, some of fundamental importance, not only biologi- 

 cally, but to physics and chemistry as well. His remarkable investi- 

 gations in osmotic pressure have strongly influenced the work of 

 subsequent workers in pure physics and chemistry, and their great im- 

 portance has been fully recognized by these investigators. Pfeffer's 

 extensive studies on plasma membranes and the phenomena of irrita- 

 bility include many papers of the first importance. During his stay in 

 Tubingen he inaugurated a series of publications " Untersuchungen 

 aus dem botanischen Institut zu Tubingen" modelled on the similar 

 publication issued from the botanical Institute in Wiirzburg under the 

 direction of Sachs. This publication ceased on Pfeffer's departure 

 from Tubingen. 



Pfeffer's best known work is -his great text-book, Handbuch der 

 Pflanzenphysiologie. This was translated into English and was for 

 many years the standard work on the subject. 



Pfeffer's name is also associated with the well-known periodical. 



