86 



TROPICAL CLIMATOLOGY 



Sinhalese, living nearer the Equator, are distinctly less pigmented than the 

 Tamils of the warmer regions of Jaffna and South India. 



There is also not the slightest doubt that the European living in tropical 

 countries becomes darker, a fact which specially applies to the descendants 

 of the settlers. On the other hand, according to Finsen, the dark colour of 

 the negro diminishes to a sensible degree in Europe. 



It must be noted, however, that a certain number of Europeans do not 

 become sunburnt in the tropics. On the contrary, their skin, especially in 

 localities where the climate is damp and hot, may take a peculiar whitish 

 colour, even in cases in which the blood examination does not reveal any 

 sensible decrease in the amount of haemoglobin. As a result of an extended 

 series of observations made by medical officers in the Philippine Islands, 

 Chamberlain reports that the red cell counts averaged 5,200,000 per cubic 

 millimetre in healthy American soldiers, averaging twenty-six years of age, 

 after twenty months' service near sea-level, which count does not differ from 

 the normal as at present recognized for healthy young men in the Temperate 

 Zone. The haemoglobin averaged 89-6 per cent., and the colour index o*86 

 to 0*87, both of which were a little low, but not sufficiently so to indicate a 

 definite anaemia. He believes that the pallor mentioned above is as a rule 

 due to a superficial ischaemia. 



The effect of tropical light on man has been made the subject of a special 

 memoir by Woodruff, who points out that all over the globe the people who 

 live nearer the poles are blonder than those residing near the Equator. He 

 thinks that insufficient pigmentation, by permitting the penetration of the 

 chemical rays, conduces to the increased activity of the mind and vigour 

 in the muscles which is found in new-comers in the tropics. This condition 

 of excitation causes them to overdo themselves sooner or later, and so to 

 produce a feeling of exhaustion which he describes as tropical exhaustion. 



He further considers that white men cannot become acclimatized in the 

 tropics, and also that they should be protected by clothing opaque to the blue 

 and ultra-violet rays. For this purpose he says that the outer clothing should 

 be white, grey, or yellow, because heat will be least absorbed by these colours, 

 while the underclothing should be black or yellow, to stop the ultra-violet 

 rays. For office-workers and others not exposed to the direct sun-rays lie 

 advises black or dark blue, but he states that it is not known whether blue 

 or black excludes the ultra-violet rays. 



He also strongly advises opaque head-gear, as he says it is surprising how 

 transparent the scalp and skull are to light rays, and that it is certain that the 

 ultra-violet rays pass through them. 



He points out the nuisance of the glare from houses painted white in the 

 tropics, and mentions the better colours of green, dark yellow, and brown. 

 The gradual disappearance of the white buildings in the business part of 

 Colombo, and the appearance of new buildings coloured brown, indicates the 

 correctness of his views. 



While it is not possible to agree with all or even with many of Woodruff's 

 statements, there is no doubt whatever that there is a great general truth in 

 what he says, though many of the matters upon which he touches are purely 

 speculative. 



On the other hand, there is most urgent need for protection from 

 sunhght both as regards the eyes and the whole body. With regard 

 to the effect of the tropical sun on man and animals, some most 

 interesting experiments have been performed in the Philippine 

 Islands by Aron and Gibbs separately. Rabbits and monkeys — ■ 

 i.e., animals with limited power of physical heat regulation — die if 

 exposed to the sun's rays. The body temperature of these animals 

 rises to febrile heights, while the post-mortem reveals haemorrhages 

 into the meninges, and in the case of monkeys into the heart. If, 

 however, the increase of heat absorbed from the sun's radiation is 



