Mat 4, 1917] 



SCIENCE 



439 



should exceed a certain limiting quantity. If 

 there is not enough material available or if 

 for anatomical reasons the material can not 

 reach a bud the latter will be prevented from 

 growing. 



6. We do not wish to discuss the nature of 

 the substances which cause the growth, but it 

 is important to know that the leaves will form 

 no shoots or only very few if kept in, the dark. 

 Six pairs of leaves from the same node were 

 suspended in moist air, one leaf of each node 

 in the dark, one in the light. After one month 

 the six leaves in the dark (weighing 11.65 gm.) 

 had produced only 3 etiolized shoots weighing 

 0.016 gm., while the six sister leaves in the 

 light (weighing 8.03 gm.) had produced 24 

 normal shoots, weighing 0.544 gm. The shoot 

 production in the light was therefore more 

 than thirty times as great as that in the dark. 

 This may mean that the material from which 

 the new shoots are produced in a leaf is itself 

 to a large extent a product of or dependent 

 upon the assimilatory activity of the leaf. 

 The root formation did not seem diminished 

 in the dark, and at first it seemed even en- 

 hanced. 



Jacques Loeb 



SOCIETIES AND ACADEMIES 

 THE BOTANICAL SOCIETY OF WASHINGTON 

 The 117th regular meeting of the Botanical So- 

 ciety of "Washington was held in the assembly hall 

 of the Cosmos Club, at 8 p.m., January 2, 1917, 

 President T. H. Kearney presiding. 



The program was devoted to the subject of 

 Plant Introduction, under which the following 

 papers were presented: 



The Need of More Foreign Agricultural Explora- 

 ■ tion (illustrated) : De. David Faibchild. 

 Dr. Fairchild called attention to the need of 

 more foreign exploration and to the fact that up to 

 the present time a comparatively small amovmt of 

 money had been expended on this important work. 

 The most successful type of agricultural explora- 

 tion is that carried on by men interested in par- 

 ticular crops. The need of studying the methods of 

 agricultural production in foreign countries, some 

 of the more important recent introductions, and the 

 difficulty in getting people to adopt new foods 

 were emphasized. 



The Wild Eelatives of Our Crop Plants; Their 

 Value in Breeding; How to Secure Them (illus- 

 trated) : Mr. Walter T. Swingle. 

 The usefulness of the wUd relatives of our crop 

 plants in securing such desirable qualities as 

 hardiness, earliness or lateness of blooming or of 

 ripening, disease resistance, extra vigor, etc., were 

 pointed out. As an example, the desert kumquat of 

 Australia, which does not resemble closely in gen- 

 eral appearance true Citrus, was found to be a most 

 desirable plant for the successful breeding of hardy 

 and drought-resistant citrous fruits. Mr. Swingle 

 stated that a properly digested technical knowl- 

 edge of the wild relatives of our cultivated plants 

 is an indispensable foundation for all efficient plant 

 introduction and plant breeding. 



The Introduction of Foreign Plant Diseases: Mk. 



E. Kent Beattie. 



Mr. Beattie separated all diseases of economic 

 plants into two groups: (1) Those which have 

 passed from native plants to the introduced hosts; 

 (2) those which have been introduced, such as 

 citrus canker and chestnut-bark disease. Diseases 

 are brought in on diseased crop plants introduced 

 for commercial use or for scientific purposes, or 

 the spores may be carried in on plants not affected 

 by the disease. Commercial-plant introductions are 

 inspected usually by entomologists and fungus dis- 

 eases are often not detected. The material im- 

 ported by the TJ. S. Department of Agriculture 

 undergoes rigid inspection and retention in case 

 any diseases are suspected. During the year 1916 

 the Federal Horticultural Board found on the ma- 

 terial imported by the U. S. Department of Agri- 

 culture 157 different diseases. 



The Protection and Propagation of Plant Introduc- 

 tions: Dr. B. T. Galloway. 

 Dr. Galloway called attention to the rapid 

 change in public sentiment in the matters of plant 

 sanitation and hygiene and to the need of a con- 

 structive policy in adequately protecting our crop 

 plants, and at the same time not closing the doors 

 to the development of new crop industries. He also 

 discussed a number of the problems confronting the 

 Office of Seed Plant Introduction. 



The 118th regular meeting of the Botanical So- 

 ciety of Washington was held in the assembly haU 

 of the Cosmos Club, at 8 p.m., February 6, 1917. 

 Forty-four members and fourteen guests were pres- 

 sent. 



