INSECTS AND DISEASE. 657 



ing the indigenous air of any natural environment should be, and 

 without warning of danger, a means of death. Such a supposition is 

 inconsistent with that general beneficence of Nature as exhibited in 

 the signals of danger, instinctively recognized by all living things, 

 when contemplating their natural enemies, and when in the presence 

 of conditions that are destructive to life. 



Man naturally loves beautiful things woman and the flowers. 

 But the serpent also is beautiful superficially smooth, tapering in 

 form, elegantly elastic, absolute in symmetry, undulating in motion, 

 every element of beauty in woman finds its counterpart in the snake ; 

 yet we love the one, loathe the other loathe it because we have in- 

 herited the instinct that tells us it is one of our natural enemies, whose 

 touch is destruction ; and, when sight is not sufficient, the rattle is 

 added, so that even in darkness we may hear the warning note of 

 danger. 



When man is prompted by Nature to invade a swamp in pursuit 

 of fowl and fish, his natural foods, it can not be that the silent air 

 he breathes shall, like a subtle enemy, and without any admonition, 

 destroy his life. But when night comes, should he there lie down to 

 rest, the annoying puncture of the mosquito and its siren-song, like 

 the warning note of the serpent's rattle, would emphatically and per- 

 sistently tell him, " This is no place to sleep ! " 



The mosquital origin of malarial disease is in this respect, there- 

 fore, more in accord with the beneficence of Nature's arrangements 

 than is the conception of malarial fevers being produced by the respira- 

 tion of a marsh-vapor. 



I have before referred to " color-protection " as a means of defense' 

 from natural enemies. Acuteness of audition is another well-known, 

 means. It curiously happens that some forms of fever are followed 

 in those who convalesce by a remarkable acuteness of hearing, which 

 lasts for weeks and months, thus indicating another phase of adapta- 

 tion to environment, an additional means of recognizing the warning 

 note of the inoculating mosquito, or other insects inaudible to ordi- 

 nary ears. Dr. J. B. Allan refers to this symptom in his description 

 of a remittent fever prevailing on the African sea-coast (" Monthly 

 Journal of the Medical Sciences," August, 1841, page 545). He says : 

 "The acuteness of hearing sometimes came on during the second day 

 in those who recovered. It was very distressing for the first six 

 weeks or two months of convalescence ; and every wave that burst 

 on the distant reef was counted with pain and even dread." 



If the mosquital origin of malarial fevers be correct if protec- 

 tion from mosquital inoculation protects from ague the means of 

 prophylaxis from malarial disease will not be difficult. It comprises 

 the following items : 



1. Personal protection from all winged insects, especially during 

 evening and night, by gauze curtains, window-screens, or clothing im- 



TOL. XXIII. 42 



