September 22, 1922] 



SCIENCE 



337 



By far the most generally used of these 

 philosophical methods is that of Realms, Re- 

 gions and Zones. These are all based on the 

 idea that large numbers of species have the 

 same range, and that by picking out some of 

 the conspicuous forms and mapping their 

 ranges one has ipso facto a set of regions, to 

 ■which other ranges may be referred, and with 

 which other ranges should agree. 



This is, in some degree, true, but in nearly 

 every case in which the ranges of any two 

 species agree, the agreement is due to the 

 geographic factors and not to the zoologic 

 factors. 



It is obvious that the zoogeographical realms 

 are nothing save and except the great land 

 masses with lines drawn to correspond to the 

 physiographic barriers. There is a great philo- 

 sophical difference betiveen such terms as 

 Holarctic Fauna and Holaretic Region. In 

 the first case we speak of zoological matters in 

 terms of zoology, in the second of geograph- 

 ical matters in terms of mythology. 



The Palearctde fauna is an aggregate of spe- 

 cies and may invade (in fact has invaded) 

 Australia without forfeiting its name. 



It occupies, in the main, territory distinct 

 from that of any other fauna, and this by 

 virtue of the Sahara and the Himalaya, but in 

 eastern China there is a broad area where 

 Palearctic and Oriental faunas intermingle and 

 where no line can be drawn which would de- 

 limit the range of more than a few species. 



In Malaysia, Oriental and Australian faunas 

 overlap in the same way. Van Kampen ("The 

 Zoogeography of the East Indian Archipel- 

 ago," Amer. Nat., XLV, 1911, p. 537-560) has 

 shown that Wallace's famous line is as myth- 

 ical as the Jack of Diamonds. 



All lines of this sort apply primarily to the 

 animal on whose range they are based (and 

 theoretically should be shifted when the range 

 is extended) ; secondarily to its parasites, com- 

 mensals, prey, etc.; and thirdly to animals of 

 very similar constitution, origin, or habits. 



Where zonal lines coincide with physio- 

 graphic barriers there is a noticeable change in 

 fauna within a few miles, where there is no 

 barrier there is a broad region wherein each 

 species is a law unto itself. 



In no case can the boundary of a faunal 

 zone, as such, be seen. 



As, in cases where the zonal lines really 

 mean a sudden change in fauna, there is also 

 present a sharp change in toisography, and as 

 this topographical change can be seen with 

 the greatest ease (and as, in eases where the 

 zonal lines are based on ranges of a few spe- 

 cies, and do not indicate a sudden change in 

 fauna, there is no sharp change in topog- 

 raphy), it seems high time to cease disputing 

 about zones and to use terms which have some 

 meaning. 



The zones are frequently described as being 

 based on temperature and the lines as corre- 

 sijonding to isothermal lines. Apart from the 

 objection that no one can see an isothermal 

 line, the temperature measurements for the 

 zones are not the bases on which these areas 

 are delimited, but are merely the temperatui'es 

 for areas previously delimited by other means. 



Once established the zones have persisted in 

 spite of the extensions of the ranges of many 

 animals on which the zones were originally 

 based, and it is a question whether the range 

 of any one species corresponds with the lines 

 drawn on faunal zone maps. 



A second method is the use of "major en- 

 vironments" and "minor environments," which 

 was put forward with considerable diffidence 

 in ShuU, Larue and Ruthven, "Principles of 

 Animal Biology," 1920. 



These are essentially plant formations or 

 forest areas. In some ways they are more 

 serviceable than zones as plant formations can 

 be seen. Also plants are somewhat more inter- 

 dependent than animals and hence the ranges 

 of more plants might reasonably be expected 

 to coincide. Furthermore, plant formations 

 play a large part in providing animal en- 

 vironment, as forest, prairie, etc., a part recog- 

 nized in the term "major environment." 



But, after all, the same objection holds in 

 this ease as in the case of the zones. Where 

 there is a sharp change in plant formation 

 there is usually a sharp change in topography 

 or in soil conditions. Without such change 

 there is no marked change in plant communi- 

 ties. 



There is certainly an inherent absurdity in 



