456 PROCEEDINGS OF THE ACADEMY OF [1881. 



these closely allied species to have been originally of one parent- 

 age, how did the power in one case to change to bright color, or 

 in the other to resist the tendency to color, originate ? If by 

 chemical power alone, it would occur at once, as a piece of white 

 wood is at once browned by fire, but with the vital principle 

 opposed to this chemically destructive principle, it would take 

 more time to accomplish this change; and the change, once made, 

 would again require more time to again alter the fixed condition. 

 This is essentiall}^ the foundation of the law of heredit}^, and under 

 its operation we could not reasonably look for a change in the color- 

 ing power of these European trees although light were an active 

 agent, under even more than five or ten inherited generations. 



At any rate we have in these salt-marsh plants the evidence that 

 the plants of one country, in that country colorless, can be made 

 to take the most brilliant colors when growing in ours. That 

 these plants had one primarj^ origin is certain, though the ancestry 

 ma}' have been separated b}^ thousands of years. We know that 

 plants introduced at once do not change at once — hei-edity forbids 

 it. We may assume therefore that it was only after some genera- 

 tions on the American coast, under the influence perhaps of 

 American light, that these European plants showed their Ameri- 

 can colors. We can see in these annual plants, with a new gener- 

 ation every year, the results in numerous generations, as we 

 cannot see in the slower reproducing tree. 



Mr. Meehan thought that though we could not say we had yet 

 reached an unchallengeable solution of the cause of autumn color 

 in American foliage, considerations like these brought us nearer 

 to the end. 



November 8. 

 The President, Dr. Ruschenberger, in the chair. 

 Twenty-six persons present. 



On Movements and Paralysis in the Leaves of Rohinia. — Mr, 

 Thomas Meehan said that an inquiry of Prof. Sargent for a trunk 

 of Rohinia viscosa for the National Forestry Census, had led him 

 to look closely into the history of Rohinia in general, with some 

 interesting results. 



Though our text-books gave " Virginia and Southwards " as 

 the native location of the tree, no one seems to have collected it 

 of late years. Indeed herbarium specimens generally seemed to 

 be from cultivated plants, and he could find nowhere direct 

 evidence that it had ever been found wild by any botanist since 

 its original discovery by Wm. Bartram, as we learn from his 

 " Travels," and Michaux, as recorded by Ventenat in his " Plants 

 of the Garden of Cels," towards the end of the last century. In 



