April 17, 1903.] 



SCIENCE. 



607 



consuming the thirteen pages on which he 

 discusses the factor of light entirely, with 

 explanations of the physiological influence, 

 although in passing he mentions its ecologic 

 value as follows: 



"The importance of light from the 

 standpoint of plant geography, although 

 in its influence upon form and life of the 

 plant significant, is much less than that 

 of temperature and hydrometeors ; the dif- 

 ferences in light intensity from climate to 

 climate are insignificant in comparison with 

 these factors. Yet, until Wiesner accentu- 

 ated this influence it had usually been un- 

 dervalued. The difference in intensity of 

 light in the different climatic zones and the 

 increasing duration of sunlight from the 

 equator to the poles leave their impression 

 upon the vegetation. Still more impor- 

 tant, to be sure, is the significance of light 

 for plant topography, since for the char- 

 acterization of the single formations of a 

 region the great differences of lighting are 

 important. ' ' 



But for any expansion on this part, 

 namely, the topographic importance of 

 light, we look in vain. 



The relative tolerance or endurance of 

 light among the tree species within a given 

 climatic range is probably the most impor- 

 tant ecologic factor which determines the 

 character of the association. The tolerant, 

 if adapted to climate and soil, must ulti- 

 mately drive out or reduce in number the 

 intolerant or light-needing, even though 

 perfectly adapted to climate and soil. This 

 accounts for the sporadic occurrence in the 

 mixed maple-beech-hemlock-spruce forest 

 of such light-needing species as the black 

 cherry, the ash, the elm. It accounts for 

 the existence of the most intolerant bald 

 cypress or larch in the swamps, where their 

 competitors could not follow. It accounts 

 for the change of forest type under the 

 influence of man, the alternation of species 

 observed on burns and slashings. 



An ecological study of the relative shade 

 endurance of our important species is the 

 most important need of the silviculturist. 



And so we might enumerate any number 

 of problems of practical importance for the 

 solution of which the practitioner is wait- 

 ing. And as in other sciences, which were 

 first deduced from empirics and now direct 

 the practice, so for ecology has come the 

 time to direct the practice. 



B. B. Fernow. 



Cornell Univeesity. 



WORK OP THE LIOK OBSERVATORY.* 

 The Lick Observatory suffered an irrep- 

 arable loss in the untimely death on Au- 

 gust 12, 1900, of Dr. James Edward Keeler, 

 director from June 1, 1898. Our appre- 

 ciation of his worth has not grown dim 

 with time. Dr. Keeler 's last observations 

 were made with the Crossley Eeflector in 

 the hope of recording the image of a ninth 

 satellite of Saturn, reported to exist by 

 Professor W. H. Pickering. No trace of 

 the satellite was detected, but the plate of 

 June 28, 1900, led to the discovery of an 

 asteroid, 1900 GA— probably the faintest 

 one known. 



While the Observatory is preeminently 

 an observation station, yet it is not so in a 

 narrow sense. Success in observational 

 work demands: (1) EInowledge of what 

 has been done by others; (2) knowledge of 

 pending problems, and of the most prom- 

 ising methods for their solution; (3) 

 knowledge as to how observations will be 

 used, and when they should be made, in 

 order that they may bear most efficiently 

 upon the problem. An institution whose 

 efforts were confined strictly to securing 

 observations would soon be making inferior 

 observations. Progressive observers must 

 be acquainted with the theories of their 



* Abstract of the Director's Biennial Report, 

 Lick Observatory, University of California, July 

 1, 1900, to July 1, 1902. 



