246 THE JOURNAL OF BOTANY 
least to distinguish the native or erreee aliens from the 
mere casuals, if these are mentioned at all. In respect of aliens 
or plants that owe their presence ren a district to cans aid, inten- 
; ee or involuntary, their treatment is on no settled basis. Every 
admits without question species that are certainly of alien 
otigiss even such weeds of cultivated ground as disappear when 
cultivation is seas a as may be verified in too many localities in 
some parts of our country. Yet other species are not admitted, 
though they may bee met with here and there well established, oe 
at least as likely to > emgag their species in the new home 
are some native s 
Comparatively fem writers seek to analyse the floras of the 
oA? treated of with a view ed determine whence each species 
came how, its relation to man, whether assisted by him in its 
avtivel Aivectly or iidivectly, ibibo favoured or harmfully affected 
by him, its relations to its environment— especially to other species 
of plants and to animals—and other questions that suggest them- 
selves when such inquiries are entered on. It is very desirable 
that a careful and exhaustive revision of the British flora should 
differing to a recognizable degree from the ancestral t , and 
ares to become more marked in the more distant ae fone 
solated localities. An excellent example of this is afforded by the 
picduotive results of the very careful investigation of the Shetland 
flora by oes late Mr. W. H. Beeby. 
Within recent years excellent work has been done in the study 
of plant aseouiationD; but the reports on these studies are dispersed 
reports of work done on plant-remains from peat-mosses, from 
deposits, and from other recent geological formations, re- 
ins to it is 
ae, established should f find a vised in the manuals of ant 
