SECRETIONS AND EXCRETIONS 307 



effects, the immediate and the remote. The former are those 

 which are experienced at the time of indulgence or within a short 

 period after, and are due mainly to the direct action of the drug 

 on the nervous system. Probably the earliest effect is always a 

 greater or lesser degree of paralysis, which besets at first certain 

 'inhibitory centres' of the brain, and, therefore, may present in 

 the beginning an appearance of stimulation. Thus, after a small 

 dose of alcohol the heart tends to beat faster, owing to paralysis 

 of the centres which inhibit and control its movements, and there 

 may also be mental changes involving some loss of self-control. 

 A deeper degree of paralysis, involving other nervous centres, 

 constitutes obvious intoxication. This initial paralysis, with its 

 associated pleasurable sensations, is exchanged, some hours later, 

 when the poison is eliminated from the body, for the well-known 

 after-effects the temporary illness which follows a bout of 

 excessive indulgence. The remote effects are mainly gradual 

 degenerative changes in many tissues, including the brain. As a 

 rule they do not occur until after chronic excessive indulgence 

 of some months, or, more commonly, years. In England few 

 deaths occur from the immediately poisonous effects of alcohol, 

 but amongst Red Indians and others, whose tendency to very 

 deep indulgence is greater, they are more common. 



514. Alcohol is an excretion, a waste-product of the yeast 

 fungus, comparable as such to the urine or carbonic acid excreted 

 by man. Opium and nicotine, on the other hand, are real toxins 

 elaborated by the poppy and tobacco plants. They serve, like all 

 other vegetable poisons and like the toxins of microbic diseases, as 

 a means of defence against enemies. We have seen that an acquired 

 immunity to a disease is a capacity, developed under the stimulus 

 of use, to tolerate a toxin which was previously more poisonous. 

 We have seen, also, that many individuals of human races that 

 have had no previous experience of measles and other acute lethal 

 diseases, are able to acquire immunity against them, though indi- 

 viduals of races that have had long experience are able to acquire 

 it more easily. It follows that, in addition to having evolved special 

 powers of acquiring immunity against particular diseases, man has 

 evolved a general power of becoming able to tolerate toxins, which 

 again is a part of the general power of making use-acquirements. 

 Doubtless, it is on this account that experience makes the indi- 

 vidual so tolerant of opium and tobacco that he is able to consume, 

 without immediate poisoning, immensely increased doses. 



515. But no amount of experience enables a man to increase 



