14 THE POPULAR SCIENCE MONTHLY 



alcohol and other poisons, or are exposed to abnormal cold by shaving 

 of the skin, are more subject to certain infections than animals not so 

 treated. If, now, it were found that the blood factors governing resist- 

 ance fluctuated with these influences, became smaller and less con- 

 spicuous when the influences were bad and larger and more efficient 

 when the influences were good, we should then have established an 

 important concrete fact. 



But the alexinic activity of the blood varies normally within such 

 wide limits that only maximal changes could be regarded as significant, 

 and it appears that it is only as the fatal termination of certain severe 

 infections are reached — such as experimental anthrax and pneumococcus 

 infections, for example — that the alexinic power falls greatly or dis- 

 appears altogether. The determination of phagocytic activity outside 

 the body has not thus far been carried out in such a manner as to 

 indicate a functional depression which either precedes immediately or 

 develops in the course of severe infections; although certain infections 

 which take a severe course are characterized by a persistent reduction 

 in the number of leucocytes in the circulating blood. This latter phe- 

 nomenon must, however, probably be regarded as an effect and not as 

 the cause of the infection. There is, however, known at least one 

 example where paralysis of the phagocytes leads to a fatal infection 

 under conditions in which the normal phagocytes are entirely com- 

 petent to prevent infection. If to a guinea-pig a small dose of opium 

 be administered and this is followed by the injection of a non-lethal 

 quantity of a culture of the cholera bacillus, death will ensue because 

 the sensitiveness of the phagocytes to the chemical stimulus exerted by 

 the cholera poison has been diminished by the narcotic influence of 

 the opium. 



The mean phagocytic value of the blood can, however, be definitely 

 raised by certain agencies, that are at the same time and through the 

 rise in the number of phagocytes produced, useful in warding off and 

 sometimes even in overcoming infection. The means employed to 

 bring about an increase of leucocytes, or to establish a hyperleuco- 

 cytosis, suffice to maintain the high value for short period relatively 

 only, unless the stimulus is frequently repeated. A cold bath, a sun 

 bath, the injection into the circulation of a number of simple chemical 

 substances — peptone, albumose, nucleinic acid, spermin, pilocarpine — 

 are all followed under physiological conditions by hyperleucocytosis 

 and by a temporary state of increased resistance to bacterial invasion. 

 Moreover, in certain experimental infections, at least, there can thus 

 be aroused a heightened power to overcome established infections — 

 those caused, for example, by the cholera, meningitis and pneumococcus 

 germs. Perhaps the most striking example of the protective influence 

 of hyperleucocytosis is afforded by the experimental infection described 

 under the name of cholera peritonitis of the guinea-pig. If a fatal 

 quantity of cholera germs be injected into the peritoneal cavity of a 



