792 



SCIENCE. 



[N. S. Vol. XV. No. 385. 



gather obse'rvations of cirrus within the tropics 

 (see Nature, 1887-1889). These observations 

 were followed by the systematic work of Hilde- 

 brandsson who has shown that the prevailing 

 motion of the cirrus between 20°1T. and 20°S. 

 is from the east. Above these latitudes the 

 prevailing cirrus motion is , from the west. 



It is probable that between these two regions 

 of opposing winds there is a narrow belt of 

 comparative calm across which the air moves 

 very slowly from the equator. The spread of 

 the dust from Krakatoa across this region 

 apparently did not exceed a velocity of one 

 mile an hour, so that it was two months or 

 more after the eruption before sky glows were 

 observed in high northern latitudes. 



It is evident that observations on the sky 

 glows following volcanic eruptions are very 

 desirable for the study of the atmosphere. It 

 is thought that some bright sunsets observed 

 at Blue Hill last autumn may have been con- 

 nected with a volcanic eruption in May in 

 Java and subsequent brilliant sunsets in 

 Mauritius described by Olaxton. If notes 

 were made elsewhere of unusually brilliant 

 sunsets we should be glad to receive them at 

 this Observatory and also accounts of such 

 sky phenomena as may follow the eruption at 

 Martinique. 



Henry Helm Clayton. 



Blue Hill Obsekvatobt, 

 May 10, 1902. 



THE WORD 'ecology.' 



To The Editor of Science: After the fuU 

 discussion of the origin, history and use of the 

 word ecology in Science for April 11, it is cer- 

 tainly surprising to read the inexcusably erro- 

 neous statements about this word by Mr. F. 

 A. Bather in the current number of the same 

 journal. After correctly stating the meaning 

 of the word, Mr. Bather goes on to say: 

 "Haeckel and biologists generally have used 

 the word in the above sense, but of recent years 

 the botanists have wrested, or at least re- 

 stricted, the meaning of the term to the study 

 of the associations of plants in such groups 

 as alpine, sand-dune and desert plants; and 

 this is the sense intended on pp. 458, 459 of 

 Science for March 21. In a word they have 



used ' (Ecology ' instead of 'oecological plant 

 geography.'" This statement is extremely 

 misleading if not wholly erroneous. It is pos- 

 sible that some writers have so restricted the 

 term, but I cannot recall any case of it. Mr. 

 Bather cannot surely here refer to Cowles's 

 use of the phrase 'physiographic ecology,' be- 

 cause Cowles, in his elaborate paper in which 

 he introduces the phrase expressly defines ecol- 

 ogy in its full scope and shows that his use of 

 the term is by no means an attempt at a 

 restriction of it. Botanists, universally as far 

 as I know, use the word in very nearly if not 

 exactly its original broad sense, as applying 

 to all forms of adaptation of organisms to 

 their environment, and hence it is perfectly 

 proper to apply it to plant associations when 

 studied from the point of view of adaptation. 

 If it were needful I could cite columns of 

 references to prove this usage, but I will sim- 

 ply refer to the fact that ecology is used in 

 its broad sense, with no attempt at such restric- 

 tion as Mr. Bather avers, in all the modern 

 botanical text-books including Campbell's 

 'University Text-Book' just issued, in a recent 

 official publication ('Report on a College En- 

 trance Option in Botany') by the Society for 

 Plant Morphology and Physiology, and in 

 many recent special papers upon plant adapta- 

 tions. 



Quite inexcusable, further, is Mr. Bather's 

 statement that Eobert Smith, in his justly 

 praised paper on the 'Study of Plant Associa- 

 tions' (in Natural Science for February, 

 1899) does not mention the word oecology. 

 Smith uses it no less than four times in that 

 paper. Thus on page 113, Smith says, 

 "Eeiter (1885) modified Grisebach's scheme of 

 plant forms to reconcile it with later research 

 in plant oecology." Again on page 112, Smith 

 says, "In the bibliography at the end of this 

 paper a few only of the chief of these have 

 been mentioned as representative oecological 

 works, dealing with such marked forms of 

 vegetation as strand plants, aquatic plants, 

 halophytes, desert plants, etc." And he uses 

 oecological again in the footnote at bottom of 

 page 115, and again, on page 110. Mr. 

 Bather's implication that Smith did not use 

 the word oecology in connection with plant 



