THE WONDER OF LIFE 501 



a sleep-instinct or hereditary predisposition to sleep, 

 obedient rather to trigger-pulhng physiological conditions 

 than to coercive auto-intoxication or the like. 



We cannot conclude this section on sleep without sug- 

 gesting the desirabihty of trying to bring numerous dis- 

 tantly or nearly related phenomena into Hne. A great 

 reward awaits the successful investigator. Perhaps it 

 is impossible to put the numerous analogous phenomena 

 into any one series, but it would be progress to know why 

 this could not be. If we start with normal diurnal sleep, 

 we have many associated phenomena, such as (a) very 

 prolonged slumbers, (b) trance, (c) coma, {d) hibernation, 

 (e) prolonged latent hfe. If we go back again to normal 

 diurnal sleep, we have in another direction, or perhaps in 

 other directions, such phenomena as fainting, catalepsy, 

 the so-called sleep of insects, ' feigning death ', paralysis. 

 And then there are the various forms of artificial anaesthesia 

 such as chloroforming (which has, of course, been very 

 thoroughly studied), to ' the shortest way out of Slum- 

 town ', (which has been very thoroughly practised). 



The Subtlety of Life 



One of the most striking biological discoveries of the 

 twentieth century is that of anaphylaxis — a difficult term 

 for a very remarkable phenomenon which illustrates ex- 

 ceedingly well what we venture to call the subtlety of hfe. 

 To understand what the phenomenon is, some introductory 

 exposition is necessary. 



It is well known that certain common infectious diseases, 

 such as scarlet fever, produce a poison within the body, 

 and that if the patient recovers he is for the future (in most 



