RECENT SCIENCE. 829 



luctance. Altogether, some substances exercise upon leucocytes 

 a decidedly attractive power, while other substances repulse 

 them. 



As to what happens with microbes which have been ingested 

 by leucocytes, the result may be very different in various condi- 

 tions. The red corpuscles of blood, when ingested by leucocytes, 

 are digested ; globules of pus and fragments of muscular tissue 

 also are digested by means of a special ferment (discovered in 1890 

 by Rosbach). And the same happens with microbes if the leu- 

 cocytes of the organism are healthy and the animal is refractory 

 to a given disease, either from natural causes or in consequence 

 of vaccination. The bacilli of anthrax are undoubtedly destroyed 

 by the leucocytes of the dog, as well as by those of such rabbits 

 as have been vaccinated against anthrax. If the leucocytes are 

 healthy, they prevent the germination of the spores which they 

 have ingested ; but they maintain this power so long only as they 

 are healthy ; because, if the animal has been submitted to cold 

 (or to heat in the case of a frog), or if it has been narcotized,* it 

 loses its immunity. Moreover, the very affluence of phagocytes 

 to an infected place may be accelerated through nervous action, 

 or slackened by various narcotics. 



Such being the facts, it was quite natural to explain them, as 

 Metchnikoff did, by maintaining that the phagocytes are the natu- 

 ral means of defense of organisms against infectious disease. The 

 very necessities of struggle for life have evolved this capacity of 

 the organisms of protecting themselves by sending armies of pha- 

 gocytes to the spots attacked by noxious micro-organisms. The 

 struggle may evidently end in either the defeat of the phagocytes, 

 in which case disease follows, or the defeat of the microbes, which 

 is followed by recovery ; or, the result may be an intermediate 

 state of no decisive victory on each side, as is the case in various 

 chronic diseases, f 



As to the force which attracts the leucocytes toward the mi- 

 crobes, it is already indicated by the extensive researches of the 

 other school, which has devoted its chief attention to the chemi- 

 cal aspects of infection. It may be, as it is maintained by Mas- 



* E. Klein and C. F. Coxwell in Centralblatt fur Bacteriologie und Parasitenkunde, 1892, 

 Bd. xi, p. 464. 



f Besides the powers of ingesting and destroying noxious granules, the leucocytes also 

 contribute to the defense of the body by forming capsules around the granules, as well as 

 by carrying them out of the organism through the skin. Transpiration is a familiar instance 

 of the latter case. Mr. Herbert E. Dunham's observations on the Wandering Cells of 

 Echinoderms and the Excretory Processes in Marine Polyzoa (Quarterly Journal of Micro- 

 scopical Science, December, 1891), and Brunner's researches on transpiration (Berliner 

 klinische Wochenschrift, January 23, 1892), are especially worthy of note under this head- 

 ing. 



