October 17, 1919] 



SCIENCE 



365 



before its tip develops. When the plants are 

 in good condition the runners attain a length 

 of 20 to 30 centimeters or even more before 

 development of the tip occurs. When the 

 length of 2 to 3 centimeters of a growing 

 runner is kept at a temperature of 3° to 4° C, 

 development of the new plant usually begins 

 within two to four days, and very little foir- 

 ther growth in length of the runner occurs, 

 even though its length is much less than the 

 normal length of runner produced by the same 

 plant. Since each plant produces nimierous 

 runners in succession, and since the normal 

 length of runner at any given time is very 

 definite, several runners, of both earlier and 

 later origin than the experimental runner and 

 from the same plant, may be used as controls. 

 There is no wilting of the rmmer distal to the 

 low temperature zone, and the tip evidently 

 receives nutrition, for the growth and develop- 

 ment of the new plant take place as rapidly 

 as in normal runners which have attained 

 their full length. It should be noted, more- 

 over, that these runner-tips are not permitted 

 to touch the ground and become rooted, but 

 are kept suspended in air. 



Work with this method is being continued 

 and further results will be reported and ap- 

 paratus and technique more fully described in 

 later papers. 'The results already obtained, 

 together with certain conclusions to which 

 they point are summarized as follows: first, 

 the inhibiting action of the growing tip of the 

 plant upon other buds, or of a leaf upon buds 

 on other leaves, as in Bryophyllum, can be 

 blocked by a zone of low temperature which 

 does not prevent the flow of water and nutri- 

 tive substances; second, the block produced 

 by the zone of low temperature does not in- 

 volve any visible or jjermanent alteration of 

 the tissues, but is wholly reversible; third, a 

 .temperature which is at first an effective block 

 may become ineffective after a few days, be- 

 cause of acclimation of the cooled zone to that 

 temperature; fourth, in view of the above 

 facts it appears at least highly probable that 

 the inhibiting action of growing tip, a leaf, or 

 other active region of. a plant, depends for 

 its passage from point to point upon metabol- 

 ically active protoplasm, rather than upon 



purely physical transportation in the fluids 

 flowing through " preformed channels " in the 

 plant. In other words, the mechanism of this 

 physiological correlation appears to possess at 

 least certain of the characteristics of a trans- 

 missive or conductive, as distinguished from a 

 purely transportative mechanism. 



C. M. Child, 

 A. W. Bellamy 



SCIENTIFIC EVENTS 



THE BRITISH NATIONAL PHYSICAL LABORA- 

 TORY 



SiK Richard Glazebrook, as already recorded 

 ill Science, resigned the directorship of the 

 iN'ational Physical Laboratory, Teddington, 

 which he has held since its inception in 1899 

 on September 18, his sixty-fifth birthday. 



Sir Richard was principal of Liverpool Uni- 

 versity when he received the appointment to 

 the laboratory, which was founded by the 

 Royal Society, and was originally intended as 

 an extension of Kew Observatory. Wlien the 

 new buildings were opened at Tedding-ton in 

 1902 it had but two departments and a staff of 

 twenty-six. At the present time the staff num- 

 bers about 600, and building operations are 

 still in progress for the accommodation of new 

 departments in research work. 



As already announced Richard Glazebrook 

 is succeeded by Professor Petavel, professor of 

 engineering and director of the Wliitworth 

 Laboratory in the University of Manchester. 



The London Times writes: 



Sir Eiohard Glazebrook, who retires from the 

 direetorship of the National Physical Laboratory, 

 has controlled its fortunes from its small begin- 

 nings in 1899 to its present great place in the 

 scientific organization of the nation. It was first 

 intended merely to carry out investigations re- 

 quired in connection with the manufacture and 

 testing of instruments of precision, and in 1902, 

 when it was moved to new t)uildings at Tedding- 

 ton, it had only two departments and a stafi of 

 twenty-six. It has now seven scientific depart- 

 ments, a secretariat, and a staff of over 600 per- 

 sons. These deal with heat, optics, acoustics and 

 molecular physics, with electricity, metrology, engi- 

 neering, metallurgy, the forms of ships and aerial 

 machines, and aero-dynamics. It is the supreme 



