THE BOTANISTS OF PHILADELPHIA. 337 



attending the lectures in mineralogy and botany of Pro- 

 fessor Chisati, a celebrated systematic botanist of that day. 

 Returning in the summer to the University of Berlin, 

 Dr. Wilson matriculated there for one semester. In Ger- 

 many he attended the lectures of Grisebach, the greatest 

 geographical botanist of the world at that time, also those of 

 Professors 0. Drude and Reinke. In Berlin he placed liim- 

 self under Schwenclener, working in his laboratory on some 

 of Wiesner's experiments on light, securing his apparatus 

 from Professor Helmholtz's laboratory. During the vacation 

 periods Dr. Wilson visited Sachs, at Wurtemburg ; Niigeli, 

 at Munich, and in the winter of 1879 and 1880 matriculated 

 in the University of Tubingen, under Dr. William Pfeffer, 

 pursuing work under his direction along physiological lines. 

 In July of 1880 he took the degree of Doctor of Science at 

 Tubingen, with honors. In the winter of 1880 he came 

 home to America, remaining one month, when he returned 

 to Tubingen, upon the invitation of Dr. Pfeffer, to carry on 

 some special lines of work there. Returning to America in 

 1882, many flattering offers were tendered to him from the 

 West and Southwest. 



Mrs. Wilson, being in delicate health, Dr. Wilson spent 

 part of the intervening time with her in the South during 

 the winter months. Several years after the death of Mrs. 

 Wilson, he married Miss Lucy Langdon Williams, Head 

 of the Department of Natural History, Girls' Normal School 

 of Philadelphia. In the middle of the winter of 1886 

 Dr. Wilson was appointed Professor of the Anatomy and 

 Physiology of Plants at the University of Pennsylvania. 



Professor Wilson, during his vacations, spent consider- 

 able time in Florida, where he w^as enabled to study the 



