VI The Web of Life in 



multiplying within us so as to choke the system, at once 

 feeding greedily on the tissues or fluids of the body, and 

 poisoning us in every cell with the waste-products of their 

 loathsome life. It would take us too far from present 

 botanical considerations to discuss the ways in which we are 

 saved from the bacteria which so easily beset us. There are 

 happily many drugs and reagents of inward or outward use, 

 from quinine to carbolic acid, and all the other ever-multi- 

 plying antiseptics drugs which they cannot stomach. Like 

 the Acacia tree with its bodyguard of ants driving off other 

 dangerous ants, so, some tell us, we may have a protective 

 standing army of bacteria which save us from others ; at all 

 events, the widely accepted theory of Metschnikoff makes 

 us view the animal body as garrisoned by the uncoloured 

 blood-corpuscles or leucocytes which seize the intruding 

 microbes just as amoebae would do, and digest them 

 beyond the reach of mischief. But when the germs 

 become too numerous or the warders enfeebled, the 

 bacterial parasite begins its growth, and the disease has 

 set in. Such, for instance, Dr. Gulland tells us, is the 

 use of the tonsils which lie on either side of the pharynx ; 

 in health they furnish a continual succession of these 

 corpuscle sentries, while in the inflammations to which 

 they are so subject, the bacteria have been too many, the 

 defence too weak. This subject is at present under active 

 controversy, not a few bacteriologists maintaining that the 

 germicidal virtues of the blood lie wholly or mainly in the 

 serum, not in the corpuscles. 



But the most potent preventive, universal and costless, 

 is a natural one the sunlight. Miquel, of the excellent 

 bacteriological observatory of the Pare Montsouris at Paris, 

 and several French bacteriologists have shown that the sun's 

 light, even without the heat, for a few bright hours is able 

 to kill the germs which float in the air, and leave them 



