92 PROCEEDINGS OF THE ACADEMY OF [Feb., 



The twigs of the pin oak from Pennsylvania State College, College 

 Park, Maryland, University of Pennsylvania, and Lansing, Michigan, 

 showed no response in strong sodium chloride, weak ammonium nitrate, 

 strong potassium chloride, strong sodium bicarbonate and weak nitric 

 acid, while those in weak chromic acid burst their leaf buds on 

 February 15. 



Water. — University of Pennsylvania: First leaf unfolded February 

 24; flower buds burst January 27; flowers opened January 28. Penn- 

 sylvania State College: No response, as also the twigs from Lansing, 

 Michigan. 



Tulip Poplar (Liriodendron tulipifera). 3 — 



No response in any of the solutions, with the following few exceptions : 

 Potassium bisulphate (weak) — Leaf buds eased February 5. Acetic 

 acid (weak) with twigs from Auburn, Alabama — Leaf buds burst 

 February 7. 



Water. — Lansing, Michigan: Leaf buds eased February 4; leaf buds 

 burst February 6 ; first leaf unfolded February 18. Lafayette, Indiana : 

 Leaf buds eased February 7; leaf buds burst February 8. 



Carolina Poplar (Populus monilifera). — 



Corrosive sublimate (strong). — No response in twigs from University 

 of Pennsylvania, New Brunswick, New Jersey, and Ithaca, New York. 



Corrosive sublimate (weak). — Lansing, Michigan: Leaf buds eased 

 February 4. Auburn, Alabama: No response. 



Copper sulphate (strong). — University of Pennsylvania: Leaf buds 

 eased February 7; leaf buds burst February 14. New Brunswick, 

 New Jersey : First leaf unfolded February 1 1 . 



Copper sulphate (weak). — Storrs, Connecticut: Leaf buds eased Feb- 

 ruary 7; leaf buds burst February 8. Auburn, Alabama: Leaf buds 

 eased February 7; leaf buds burst February 8; first leaf unfolded 

 February 11; all leaves unfolded February 21; first leaf withered 

 March 7; all leaves withered March 11. The twigs from Lansing, 

 Michigan, and Lafayette, Indiana, showed no reaction. 



Sodium chloride (strong). — University of Pennsylvania: Leaf buds 

 eased February 7; leaf buds burst February 11. Twigs from Ithaca, 

 New York, showed no response. 



Sodium chloride (weak). — Storrs, Connecticut: Leaf buds eased 

 February 7. Lansing, Michigan: Leaf buds eased February 4. 



3 The localities are given in the table at the beginning of the experimental data 



