152 THE DISEASES AND DISOEDERS OE THE OX. 



Several other diseases, also, in which the heart's action is 

 accelerated, illustrate the same points. Looseness of the bowels 

 is often seen in children at the outset of scarlet fever, small- 

 pox, and measles, and where Dr. D. A. Gresswell, who has had 

 wide experience in fevers, has seen cases of typhus fever from 

 the very outset, the bowels have been loose for a day or two. 

 The same observer has recorded facts to show that the total 

 bodily heat is greatly increased when human beings enter- the 

 tropics, and that the increase is greater in children than in 

 adults ; and, moreover, that an increase in the intensity of light 

 brings on an acceleration of the pulse, most especially in the 

 young. 



Now diarrhoea is also apt to come on on entering the tropics, 

 and especially in the case of children. Summer diarrhoea, too, 

 may be due to various causes ; but of these probably an increase 

 of external light and heat acting directly upon the organism 

 may be of much importance. Adults also very frequently have 

 looseness of the bowels when entering the tropics. Hence, 

 together with rise of external temperature and increase of inten- 

 sity of light, there are exhibited rise of body temperature, 

 acceleration of pulse and respirations, increased action of the 

 skin and diarrhnea. In fact the associates of work are displayed. 

 The different processes involved in work have, it seems, been 

 evolved in such intimate connection that, when one of them is 

 excited, the others also tend to manifest themselves. 



With regard to acceleration of the pulse in the tropics, it is to 

 be said that Dr. D. A. Gresswell's observations on a large num- 

 ber of persons while passing from temperate through tropical 

 latitudes, on four different occasions, show that there is an 

 acceleration of the pulse in the tropics under all ordinary 

 circumstances. The pulse may, however, be slower in a tropical 

 latitude when compared with that in a colder latitude, if the 

 body be recumbent ; but this is possibly due to a weak condition 

 of the heart brought about by previous excessive action. 



On the other hand, it is to be noted that a child's temperature 

 will rise during constipation and fall when the bowels are 

 relieved, and also that the temperature of a typhoid patient may 

 rise during the convalescent stage owing to constipation, and 

 fall after an action of the bowels, induced, it may be, by the 

 administration of castor-oil, or other means. In these and 



