140 



TEMPERATURE AND HUMIDITY 



the whole body and after certain prodromes, resulting in a rapid rise of tem- 

 perature to a great height. 



In 1893 Saquel classified the diseases into (i) sunstroke, meaning the 

 erythema due to the sun's rays; and (2) insolation, meaning the action of the 

 sun on the nervous system, producing either congestion (mild form in the Tem- 

 perate Zone) or meningitis and encephalitis (severe form in the tropics); 

 (3) heat-stroke ; and (4) thermopeliosis, a combination of insolation and heat- 

 stroke. 



In 1898 Sambon defined heat exhaustion as an ordinary syncope, while he 

 considers that under the term ' sunstroke ' there is confounded an infectious 

 fever which he calls ' siriasis,' due to some micro-organism as yet not defined. 



In the period 1898- 190 7 Sir Patrick Manson, in his book on tropical diseases, 

 recognized three conditions: (i) heat exhaustion — sudden cardiac failure or 

 fainting, brought about by exposure to high atmospheric temperature; 

 (2) siriasis, an acute disease developing in the presence of high atmospheric 

 temperature, and characterized by sudden incidence of hyperpjrrexia, coma; 

 and (3) sun traumatism, or direct action of the sun's rays on the tissue, causing 

 either sudden death or a febrile condition. 



In 1905 Van Brero, in Mense's ' Handbuch der Tropenkrankheiten,* recog- 

 nizes (i) heat exhaustion, due to excessive heat from the sun or other source; 

 and (2) sun traumatism, caused by the direct action of the sun's rays. 



In 1907 Sir Joseph Fayrer, in Allbutt and Rolleston's ' System,' recognizes 

 (i) a state of exhaustion leading to syncope, and (2) an overheating of the 

 nervous centres, blood, and tissues, leading to thermic fever. 



In 1908 Brook defines diathermasia as the effect of heat on the thermotaxic 

 mechanism, and phoebism, a kind of shock due to the actinic rays from the sun. 



(For the continuation of this history see Chapter LVI.) 



It will thus be seen that authorities in general recognize the action 

 of heat and the action of sun's rays as being separate, and, further, 

 that heat may produce a syncopal condition of fever, while the sun's 

 rays may also cause syncope and fever. Some few, including 

 especially Sambon, suspect the presence of an acute specific fever 

 as being concealed in the diseases above mentioned. Others, again, 

 consider the symptoms to be toxic in origin, so that there are four 

 theories: (i) caloric; (2) actinic; (3) microbic; (4) toxic. 



CONCLUSIONS. 



Personally, we believe that high atmospheric temperatures with a 

 sufficiently high atmospheric humidity and more or less stagnation 

 of the air can produce the clinical pictures called heat-stroke and 

 heat-syncope, especially in people working hard at manual labour and 

 clad in unsuitable clothing. 



As to the reason why some persons should develop these 

 symptoms, while others living under exactly similar conditions 

 escape, we believe it to be a matter of general health and personal 

 habits, which in the one case disturb the metabolism of the body, 

 causing a derangement of physical or chemical heat regulation, while 

 in the other case this mechanism is working normally. 



The regulation of bodily heat can be disturbed by anything which 

 tends to derange metabolism or heat regulation, such as overwork, 

 lack of care in protecting the body as much as possible from heat 

 by the means indicated in Chapter III., p. 89, alcoholism, and the 

 efiects of bodily disease. 



