88 MESSRS. J. А. WHELDON AND W. G. TRAVIS ON 
II. ADVERSE CONDITIONS AFFECTING THE LICHEN-FLORA. 
Deterioration of the Flora.—Its proximity to the ocean and the physical 
and climatic conditions of the vice-county are such as would, under normal 
circumstances, be favourable to a luxuriant growth of lichens. The whole 
flora of South Lancashire has, however, been so deleteriously influenced by 
certain factors due to enormous industrial developments, that we have to 
deal with a flora, and particularly a lichen-flora, which is quite abnormal from 
that which should exist under natural conditions. 
We know there are other manufacturing districts in the country where the 
vegetation is badly affected by smoke, but we believe nowhere in the country 
does there exist an area equal in size to South Lancashire where the evil 
effects of atmospheric impurity are so widespread. We propose, therefore, 
to treat this aspect of our subject rather fully ; and we shall then proceed to 
show exactly the nature of the deterioration which the lichen-flora of South 
Lancashire has undergone. 
It is well known that no section of the flora is so much affected by man’s 
interference as that which embraces the lichens. These plants are peculiarly 
sensitive to pollution of the atmosphere and streams ; and the fact is that 
conditions inimical to lichen-growth have been so long prevalent in South 
Lancashire, that the whole facies of the original lichen-flora has been changed; 
and it is difficult from the vestiges which now remain to form an accurate 
conception of the lichen-flora as it was a hundred or even fifty years ago. It 
is only from a few records left by earlier workers, and from the gradual 
improvement of the flora as we travel northward into West Lancashire and 
Westmorland, that we can judge that lichens must formerly have been far 
more luxuriant and numerous than they are now. Ву a comparison with 
neighbouring districts of analogous physical and climatic character, we 
can form some conception of what the lichens of South Lancashire would 
be under normal circumstances, and must have been before Lancashire 
became a great manufacturing county. 
Population and Industries.—The concentration of manufacturing industry 
and of population in South Lancashire is a remarkable feature. 
Thus, according to the 1911 census, the population of the county was 
4,767,832, of which fully 43 millions reside in South Lancashire. To 
illustrate the vast increase in the population, consequent largely upon the 
enormous strides in industrial development which took place during the 
nineteenth century, it may be mentioned that the population of Lancashire 
in 1841 was 1,067,054, whilst in 1801 the inhabitants of the whole county 
only numbered 673,486. It was, then, during the nineteenth century, and 
particularly its latter half, that the whole fabric of modern industrial 
Lancashire was built up, whilst agriculture was relegated to a very 
Subordinate position. With the great increase in population, the old 
