50 
and still is ? Certainly ! That he is so is as much the 
result of climatic and other natural causes as is the hardy 
fir-tree, the Pinus sylvestris, the forests, and isolated indi- 
viduals of which give to highland glens and hill faces their 
peculiar character.* 
32. All beyond the isothermal line of 41 F. includes the 
polar zone of disease. There, malarial diseases such as en- 
danger and often embitter life in the tropics are absent. 
Climate is absolutely different from, and as nearly as may be, 
the opposite in character of that near the equator. With each 
returning spring, and regularly as plant life becomes revivified, 
disease in the form of influenza, asthmatic or catarrhal affec- 
tions occurs among the human inhabitants. These impair the 
health even when life is not destroyed, and so the majority of 
the people are short-lived. As with particular forms of plant 
and animal life, so, with regard to forms of disease which affect 
humanity, the zones in which they are indigenous are limited 
in extent'; But this cannot now be further adverted to. 
33. In our own country the relation of climatic conditions 
to the state of public health is a subject to which the attention 
of observers is at the present time much directed. It is a 
matter within the cognisance of all that particular forms of 
illness rise and fall in numbers according to season and to 
meteorological conditions. This subject was lately discussed 
before audiences in this metropolis ; f on the occasions when 
it was so, the remarks made by the eminent men who brought 
it forward were illustrated by diagrams, and by these diagrams 
the relation was made apparent which exists between particular 
forms of disease and particular seasons of the year. In fact, 
inasmuch as in the vegetable world phenomena of life manifest 
themselves in their several stages according to season, and 
differently in different orders and genera, so in man do vital 
phenomena vary under seasonal influences and climatic con- 
ditions ; retrocession or decay being brought about in varying 
manners of the process, to each of which a name is given 
# Equally distinct and characteristic are other individuals of the organic 
kingdoms ; among animals the red deer, the roe, the mountain hare, the 
grouse, the ptarmigan, and so on. Among plants the mountain ash, 1 the 
dwarf birch, 2 the empetrum or crowberry, the cloudberry or “averan ” (rubus 
chamcemorus), the cranberry ( vaccinium oxycoccus ), the bleaberry ( vaccinium 
uliginosnm), and so on. 
t Lecture by G. E. Langstaff. See Transactions of the Epidemiological 
Society of London, Yol. IV., Part III., 1878-80 ; also Lecture on Weather 
and Health of London, delivered at the Eoyal Institution. See Nature, June 
23, 1881, p. 173. 
1 Pyrus aucuparia . 
2 Betula nana. 
