4 Origin of the British Flora. 
have had but slight opportunity of studying. This has 
especially been the case with regard to the lacustrine 
deposits of the Scottish Lowlands, so minutely examined 
by Mr. James Bennie. The results of these investigations 
will be found summarised in Chapters IV. and V. of this 
work. 
In the examination of our recent flora I have looked 
at the plants mainly from the point of view of the field- 
naturalist. Their climatic and geographical distribution ; 
the periods of ripening, and the means of dispersal of their 
seeds; their competition with other plants; and their 
dependence on, or destruction by animals, were the circum- 
stances especially noted—more so than critical distinctions 
of varieties and sub-species. Not that these distinctions 
are considered unimportant, but mainly because of the 
difficulty of studying them without a complete herbarium, 
too heavy to transport during constant changes of station. 
Moreover, botanists have almost ignored the essential 
distinction between a varietal form due to local conditions, 
and a true sub-species or race; for many of our named 
sub-species have evidently no more claim to such rank than 
have luxuriant garden specimens. Forms, for instance, of 
the water-crowfoot (Ranunculus aguatilis) or of the lesser 
spearwort (2. Flammula) growing in a well-manured horse- 
pond or ditch have no claim to rank as sub-species, unless 
they can be found also under more natural conditions, and 
come true from seed. Again, the prostrate maritime form 
of broom found in Cornwall (Cytzsus scoparius, var. pro- 
stratus) has similarly no claim to varietal rank, for Mr. 
Mitten tells me that seeds gathered by him grew in his 
garden into the commonerect form of broom. A botanical 
visit to the Dingle Promontory, in Kerry, in company with 
Mr. Edmund Baker, produced several instances of this 
sort. We examined Saxrifraga umbrosa and its allied 
