1891.) Wandering Celis in Animal Bodies. 519 
took place. The disease is caused by the penetration of a strepto- 
coccus; and Metschnikoff found that there were here two kinds 
of amceboid cells at work, one of which, the smaller, attacked 
the cocci in the usual manner, while the other concerned itself 
only with the taking up of tissues which had been broken down 
in necrosis. 
We have here an interesting array of facts, which have been 
graphically summed up by Osler. He says that Metschnikoff 
has likened specific inflammation to a warfare in which the 
invading forces are represented by microörganisms, and those 
who offer resistance by leucocytes. The news of the arrival of 
an enemy is telegraphed to headquarters by the vaso-motor 
nerves, and the blood vessels are used as an avenue of communi- 
cation with the threatened region. When the invaders are 
established, they live on the host, and scatter injurious substances 
which they have formed. The active leucocytes make an attack, 
and try to eat the microörganisms, and some may, die in the 
fight. Their dead bodiessform an accumulation of pus, and 
when many are slain, the battle-ground is known as an abscess. 
Either force may be victorious, resulting in the one case in the 
recovery of the animal, and in the other in its sickness or death. 
In our bodies, then, there is a standing army of movable cells, 
which may be quickly concentrated, and attack any foreign foe 
which may appear. 
With a view of determining how active the phagocytes 
actually were in attacking foreign bodies, C. Hess took a small 
glass receptacle, on the side of which was avery fine slit opening 
into its interior. He now filled this glass with a pure culture of 
whatever microérganism-he chose to use, and, leaving the slit 
open, he placed it beneath the skin of a dog or pigeon. This 
foreign body very soon caused an inflammation. After some 
time, Hess found that a multitude of wandering cells had collected 
about the glass, and upon removing it, he found that a great 
number of them had worked their way through the opening into 
- its interior, and were then actively engaged in a battle with the 
bacteria. He did not stop here in his observations, however, 
but continued to watch the movements of the phagocytes, and 
