THE PLANT WORLD. 193 



NOTES AND NEWS. 



Probably the largest specimen Empress Tree — Pmdownia imj>er- 

 ialis — in America, is in Independence Square, Philadelphia. It is one 

 of the first lot introduced into America about fifty years ago, and was 

 a gift to the city by the late Robert Buist, one of America's famous 

 nurserymen. It is now eleven feet in circumference, equalling in girth 

 some of the old American Elms that were in the plot before the Revo- 

 lution. The wood is in great demand in Japan. It is light and strong. 

 When American forests disappear, and the planting for timber becomes 

 a flourshing branch of agriculture, the Empress Tree will give a very 

 good account of herself. — MeeJians' Monthly for Noveiiiber. 



Notw^ithstanding the great amount of W'Ork that has been spent 

 on the destructive disease known as peach yellows, little or nothing is 

 actuall}^ know^n as to its nature and causes. In Science for December 

 7, Mr. O. F. Cook reviews the subject and ventures the proposition 

 that it ma}' be the result of the poisoning of the protoplasm of the 

 living cells by the bite of a small arthropod, probably a mite of the 

 family Phytoptidse. It is a well known fact that plant cells may be so 

 poisoned by mites as to become yellow and still retain their vitality 

 for many months or even years, as palms of the genus Thrinax which 

 had been infested the so-called 'red-spider.' The proving or disprov- 

 ing of this theory, which will require long and close observation, will 

 be watched with interest. 



The great work by Engler and Prantl on the Natural Families of 

 Plants (Die Natiirlichen Pflanzen familien) is now approaching com- 

 pletion. The first part was published in 1887 and about 900 pages 

 have been printed. ' This work is a Genera Plantarum, that is a de- 

 scriptive of all known genera of plants. Dr. Engler now announces 

 the inauguration of a still greater work (Das Pflanzenreich) which is to 

 contain full descriptions of all known species of plants. When we 

 remember that there are upwards of 300,000 species now known, we 

 can gain some idea of the vastness of this undertaking. It will take 

 20 or 30 years for its completion and will of course fill thousand of 

 pages. We shall give a more complete account of this work when the 

 first number (which will be the family Musacew) is received. 



