August 23, 1917] 



NATURE 



down by diffusion and arrests emigration, and I want 

 you to notice on the right of the figure (and more 

 clearly in the inset) that the few white corpuscles which 

 were beginning to emigrate when the salt solution 

 overtook them are broken up and destroyed. By that 

 tripsin will be set free. 



*i * 



Fig. 6. — Magnified view of the leucocytie layer in the case 

 where strong salt solution was superposed upon the 

 white clot. 



I next show you what happens when microbes have 

 been implanted into the blood. Those microbes— sup- 

 posing always that they are the sort that can pro- 

 liferate in blood — grow "out into colonies. In Fig. 7 

 is shown what happens when an excessive implantation 

 has been made, and the bacterial colonies come up very 



7. — Leucocytie emigration restrained by excess of streptococcic 

 infection. 



.!y in the blood. You see here that emigration is 

 iy arrested. If that were to happen in infected 

 s it would mean that the organism was there 

 j^ up the combat against the microbes. 

 . in Fig. 8 we have again streptococcus implanted into 

 :he blood, but this time it is a much more sparing 



XO. 2495, VOL. 99] 



implantation. And here, as you see, the leucocytes 

 are carrying out a raid against the microbes, eacli 

 leucocyte ingesting and filling itself full with microbes. 

 In Fig. 9 I show you what happens when we make 

 into the blood a very heavy implantation of the gangrene 

 bacillus. Here in the neighbourhood of the leucocytie 



/ 



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Fig. 8. — Leucocytes emigrating and attacking a colony of streptococci. 



layer things are for the moment going well with the 

 leucocytes, for they are actively phagocytmg. But farther 

 away from that layer there are ver\' numerous colo- 

 nies of the gangrene bacillus, which are growing un- 

 impeded. The omens are consequently unfavourable. 

 You can see in your mind's eye what is going to 



Fig. 9. — Leucocytes emigrating and attacking colonies of 

 the gas gangrene bacillus. 



happen. In the first place, all further emigration of 

 leucocytes is going to be anested; and, in the 

 second, the leucocytes which have already emigrated 

 and ingested microbes will, instead of successfully 

 digesting them, be gradually poisoned by bacterial 

 toxins. And when, the leucocytes are killed, their 



